137GB hard drive limit in a Dell 9300

(Continuation of the thread "XP won't boot with large hard drive" - not really an XP problem, but a Dell BIOS limitation it seems...)

I am now wrapping up my second go-round with this issue, hopefully wiser and safer, not to be repeated again; with a number of lessons learned as I shall explain.

Repeating the basic info
Dell 9300
Windows XP Pro SP3 Build 2600
BIOS A05 9/19/2005
Replaced the original 80GB drive with either a 160GB or a 250GB drive, partitioning questions, etc.

As I said previously, this is my second time on this ride. I have now, just this afternoon, gotten back to a fully functional system. By way of review, I had been using a drive which I had mistakenly formatted to a 133GBb which I thought [incorrectly] was safely under the 137GBd limit. I was confused about the 137GB being a decimal bytes value rather than a powers of two value (see my previous posting for these details).

The process leaves me with a few observations:

1) My first step was to try DEFRAG on the 160GB(physical)/133GBb/143GBd drive that I had been using for a year and suddenly refused to boot past the "Load PBR1 Done" message (or something like that). Reasoning that something had been written to the upper reaches of the drive which prevented it from being read by the BIOS, something which the BIOS needed to access during boot.
a) The first DEFRAG left a high block clear at the top of the drive (according to the visual map) so I re-ran DEFRAG again.
b) Once the visual display looked like the top half of the drive was empty, I took it off of the USB connection and swapped it with the internal drive to try booting from it. => No Sucess
c) I put it back on the USB adapter and reran defrag again for the third time. Maybe the visual map is not enough resolution to show every single 4096 byte block that is allocated everywhere? I also ran all the partition checks that EaseUS offers, which found no problems at all. Swapped back to the internal drive, and this time it booted! Go figure. Must have been something that took multiple DEFRAGs to cleanup. LESSON: Don't give up if the first run or even two doesn't cure it.

2) Now that I had the most recent drive booted, not wanting to waste it, I did two things:
a) First I ran a complete one-time backup with my Norton Ghost software to a big WD MyBook 500G USB file store disk.
b) Second, I loaded up a 250G(physical) drive I had on the USB adapter, deleted all the partitions, created a 127GBb partition, created a partition of all remaining space which was about 106GBb. I formatted both with NTFS.
c) I vaguely remembered that I had trouble when I was doing this a year ago, when I copied to a new drive when it was on the USB adapter, because the drive letter got stuck at E: or F: and would not revert to C: when I installed it internally.
d) Despite the fact that I was expecting that this (c, above) might happen again, I figured I would try doing a disk copy from the 160GB(physical)133GBb/143GBd [oversize] drive which I was now successfully booted onto, to the newly formatted 250GB(physical)127GBb partition. The diskcopy said it completed successfully and it verified correctly. I swapped the drive into the internal slot and tried to boot, but it hung up at the Windows Logo screen, repeatedly. The second time I tried to boot, it realized it had failed to boot and so it ran chkdsk to verify the drive. I was surprised to find that this brand new drive, freshly formatted had some errors, cross linked files specifically! I also noticed that ChkDsk was calling this drive F: still So my suspicion in (c) above was verified. Okay, that isn't going to work... Hmmm...
e) I put the 250GB Physical drive into the internal bay, and booted to my Norton CD (f12 etc.). Then I deleted the second partition on the drive (more about this decision later), and reformatted the 127GB first partition, which now was assigned as the C: drive.
f) I plugged in my external WD MyBook drive where the new backup had been stored. I did a system restore to the 127GB partition on the new internal drive. When it had completely verified everything, I rebooted and it successfully loaded with no issues.
g) Now I have a 250GB(physical) drive with a 127GBb boot partition, and 106GBb of un-partitioned space which would be nice to partition for data and media storage, but I am concerned that this could cause trouble. More about this later.

3) Backing up to some theory for a minute, BIOS of course stands for "Basic Input Output System." This is the software in non-volatile ROM, EPROM, or Flash memory (aka "firmware" ) which the CPU reads first upon boot. This BIOS code has to know how to talk to your motherboard hardware, ports, drives, screen, keyboard, mouse, etc. We often think of it as only doing this during the boot process, but I believe it always is the code interface between the operating system calls and the hardware responses. When Windows (or Linux, or whatever) wants to do get something from the keyboard, the OS asks the BIOS for the keyboard data, the BIOS goes out and reads the keyboard physical interface, and the BIOS passes the data to the OS. Likewise with disk access. So if the BIOS cannot handle any address larger than 137GBd/127GBb, what this literally means I suppose is that any attempt to write to a higher address will wrap around into the lower addresses (which is what numbers normally do in a computer when you exceed their capacity). The partition program may well be able to create a higher partition, but if the BIOS does not use a variable large enough for a larger number of sectors, then it is still going to get you in trouble. Yes? This suggests that any attempt to use the upper region of this drive is going to ultimately lead to the same problem all over again. I would love to be convinced otherwise, anybody care to explain where I am wrong here? Seriously, I would really like to find some reason to believe that it is safe to partition that upper region and use it, but for the moment I think I have persuaded myself that it isn't going to work reliably in the long run.

4) I also noticed a peculiarity with the Microsoft DISKPART command which I have always used for partitioning and formatting. When I initially tried to create two partitions on the 250GB(physical) drive, a 127GBb and a 106GBb, after I had created and formatted both partitions, when I went into the DISKPART "Detail" command it showed the following rather peculiar information:

Starting Ending
Type Boot Cyl HD Sect Cyl HD Sect Before Total
07 80 0 32 33 1023 254 63 2048 266335304
07 00 1023 254 63 1023 254 63 266340352 222054400

Look at the Cyl/HD/Sect for the end of the first partition, and those for the beginning and end of the second partition. This cannot be right, but that's what DISKPART gave me.

So maybe the problem with the second partition was only that DISKPART cannot handle larger drives properly. So I went ahead and bought the EaseUS Partition Master Pro software which allows you to burn a bootable CD. This software clearly says it will handle drives up to 2TB. But I am still concerned about that BIOS limit. What good does it do me to create larger partitions, if the OS is going to tell the BIOS to write stuff to a partition which exceeds the BIOS's ability to address physical space?

Anyway, that's where I am at today. The system seems to be working well with a 127GBb partition, but I would really like to believe I could safely use that upper physical space which is presently un-partitioned.

Hoping someone is still awake enough after reading all of this.

Thanks!