Here we go. A little info about computers, hard drives, and what makes a computer fast or slow, etc...
A computer is made up of electronic parts. The speed of these electronics is in the nano-seconds, etc... the only mechanical device on your computer is the hard drive. It is the only device rated in mili-seconds. Therefore it stands that a hard drive is a major bottleneck in your computer. That is why servers use SCSI, Fibre channel, solid state hard drives, etc... To get a fast computer you need a fast hard drive.
This is why I laugh every time somebody asks me what kind of computer I own. I say its an Opteron 162 or whatever running on an Abit AB9 Quad GT or something like that. It's homebrew. The first response I usually hear is huh??? Is it 3GHz or what? I reply 1.8GHz or so. They say I have an HP from Staples that is a Pentium 4 3.2 GHz and they think their system is twice as good. Bull crap. Everyone rates computers quality in terms of CPU speed and I see way too many shops selling multi hundred dollar upgrades to the computer CPU for their packages instead of offering upgrades to hard drive, RAM, graphics cards for the same money and keeping a stock CPU. These people don't realize that you need a $500 graphics card to play games to the level they desire. And they don't realize that you need tons of RAM (to a cetian limit) and a good hard drive.
I remember in the past when 5400RPM was the thing. Adding a 7200RPM made a world of difference. I'd go from 20 seconds boot up time to 10 seconds. And SCSI made a world of difference too. Your hard drive is pumping pretty much 100% of the time while your computing and the faster your drive, the faster your system.
Now the hard drive is mechanical and slow remember. It can never keep up with the full speeds of SATA 1 or SATA II. Those are just interfaces, those are the speed capabilities of those interfaces, if you had devices that could work that fast. SATA is not just for hard drives, you can plug anything to SATA just like USB. Its just that nothing is made besides hard drives and soon DVD drives, so everyone assumes that the speed of SATA is the speed of your hard drive.
The speed of a hard drive comes mostly from its rotational speeds and access times. You can get the specs of access time in mili seconds and the rotational speeds in RPM. IDE-133 was fast enough for all current hard drives as they are only mechanically fast enough to run at around 100-133 MB/sec or so. This is why the Raptor is still faster than all curretn SATA II drives even though the Raptor is only SATA 1. The raptor is 10,000 RPM and has better access times. SCSI works in the same principle by have high RPM and very fast access times.
A way of thinking of this is by comparing it to mice. Is a USB mouse faster then a PS2 mouse? USB is faster than PS2 so the mouse has to be faster right? No, its the same mouse with a better interface. Same as hard drives, same drive mechanically, better interface. Hot swapable, better cables, no jumpers, same speed. As hard drives get faster SATA will be able to support these advanced speeds.
With 7200RPM and faster access times, you won't notice much difference between a SCSI drive or raptor drive and a normal SATA drive. I think you'd be better off going with SATAII and higher capacity 320GB+ drives. Capacity is worth more than speed for most people.
Windows operates off the C:\ drive. So while computing and using windows your hard drive needs to seek through the C:\ drive most of the time. That's why its good to make a seperate 20-30GB partition just for windows. Keep all your installs and data seperate from the C:\ and it will speed up your computer. You hard drive doesn't need to scan through all your 80GB of MP3s just to use windows. I've seen too many people with only a 200GB C:\ drive on their HP or DELL and they have 150GB of videos and music all over the place. First of all they have no clue where all their stuff is, they loose all their data everytime they fprmat C:\ and their computer is slow as hell since they hard drive needs to scan through 200GB of crap.
So to speed up your computer partition and use your drive properly. If you need extra speed get a RAPTOR drive just for windows. a 36GB is fine. if you need even more speed get those Seagate 15k RPM drives if they still exist. But your going to pay a lot for the drive nad the required controller.
So don't worry about SATA 1 vs SATA 2. Look at specs and access times for hard drives and benchmarks. The interface means nothing. A raptor SATA 1 is faster than a 7200RPM SATA 2. SCSI is still king although regular SATA drives are approaching it.
In my honest opinion, a couple of SATA II 320GB drives set up as a RAID and partitioned properly will provide good enough performance for most people, with the capacity we desire, at the lowest possible price.
Raptors and SCSI are reserved for servers where all the users have network storage, and for gamers and overclockers who demand top benchmarks just for the fun of it.