I just bought, and flashed this drive:
http://www.newegg.co...N82E16822136280It's a 320GB drive, 7200 RPM, it was only $5 more then the 250GB variant, so what the hell I thought.
After flashing and moving everything back over, I tryed installing, and playing the installed game off the drive, and I noticed with the 7200 RPM vs the original 20GB [5400 RPM] drive, the install was much faster on borderlands at least. I thought that the flashing would make the drive run in 5400 RPM mode or something, but it seems to be much faster then 5400 RPM would allow. Load times didn't change to my knowledge, maybe by a few seconds. I also installed Halo 3, Gears of War 2, Fable II, and Left 4 dead. I am unsure if those install times changed however since I never installed them on my old drive.
Final thought:
Buy the 7200 RPM drive, install times are finally bearable.
I think I know the answer, but did the drive show up as 250gb or 320gb when you put it in the xbox 360?