Thinkpads Forum

I have a nice T400 (P8600, hybrid graphics, 4Gb of ram...) with a win7 ultimate on board. Still, I am not satisfied with it.

The thing is, I have a fair number of apps working in xp-mode only, and so am considering downgrading to win xp pro. Would it hit performance much?

W7 is very optimized os, XP is a bit slower

I'd guess that the performance hit won't be noticeable. Your T400 is powerful enough to run either OS quite well.

You should note that only 3GB of RAM will be available under 32-bit XP, unless you use the 64-bit version of XP. Since the T400 uses dual channel mode for memory, you still will benefit slightly in performance from all 4GB.