Storage Options / Procedures in the New Millenium

When I cut my teeth so to speak on computers as a little kid (now a big kid in college using Dad's THG forum account) there was a solid reason to dual boot. Before I had my own computer, and had to use dad's, he had it set up so that nothing I could do as an impulsive little kiddie could hurt anything of his. He used the Partition Magic Boot Manager to set it up so that my "Win9x stuff" was on a FAT32 partition (C1) and his NT4 stuff was on an NTFS partition C2). Both shared a common swap file and temp file location on D. Again, I could pretty much delete everything on my FAT 32 partition and his stuff wouldn't be harmed pretty much no matter what I did since machine would always autoboot into Win9x unless one made a menu selection within 3 seconds.

Since then we've always stayed behind the bleeding edge even when we all had our own machines. Dad's favorite OS is still "pre-MS Bloat" NT4 and there's not a Vista box among the 12 machines we have. Therefore dual booting was not really a real consideration. But now, I'm thinking of building my next box with Windows 7 RTM and I gotta wonder after doing so, will I be looking for XP because something or other just doesn't work right. So, some questions:

1. We have Acronis Disk Director Suite which so far I have only used for partitioning. Has anyone used their boot manager ? In the old machines we had 4 partitions: 0 - Boot Manager 1 - Win9x 2 - WinNT 3 - Extended Partition. Are we still limited to 4 partitions on a HD ? Would this be the preferred method these days to totally isolate one OS from the other ? The standard MS way of dual booting leaves some shared boot files on the same partition which I'd want to avoid.

2. All my current tools .... Disk Doctor, Diskkeeper, Shadow Protect Desktop .... any considerations I have to address with RAID (using what's on Asus Rampage II Extreme). I haven't seen anything that says they don't work but I have only been perusing the vendor's web sites.I'm torn between the following ATM.

a) Three 1 TB 7200.12's in RAID 5
b) Two OCZ Summit 128 GB SSD's in RAID 0 w/ one 1 TB 7200.12
c) Two OCZ Summit 128 GB SSD's in RAID 0 w/ two 1 TB 7200.12 in RAID 1
d) Two SSD's in RAID 0 and three HD's w/ RAID 5 ( a bit overkill but only cost $90 extra)

I should note that I have my iTunes and photography stuff on a separate volume on Dad's NAS and I'm using more 3 x the space his business is and he has 24 years of business records, every letter typed, every CAD drawing created, every photo taken on it . So he's a bit anxious to claim some of that room back.

I'm stretching my memory a bit and don't have the old trusty Partition Magic Manual available, but I remember that the boot files "back in the day" (Win9x / WinNT) for both OS's had to be in the first .... I dunno....8 Gigs or so. Not having the need to dual boot in recent years I haven't bothered to follow how this limitation has evolved. Do you know if XP, Vista, Win7 has similar limitations ?