I did a restore to factory state from Acer's aRecovery program for my Travelmate 2492. It left the D: partition ACERDATA untouched.
I dont know why Acer supply their PCs with the C: and D: partitions formatted as FAT32 rather than NTFS as you'd expect for XP.
The eRecovery program had no problem with the fact that I'd previously converted the two partitions to NTFS, although it did leave C: as FAT32 so I had to convert it to NTFS again after restoring.
Sadly the restoring was all a great big waste of time for me: I'm having problems with the sound on my TM2490 (see my thread "Acer Travelmate 2492 / Realtek HD Audio - distorted sound / Stereo Mix input muted
") and Acer support wanted me to see what happened with a clean installation because I'd already tried Realtek's latest drivers (which Acer don't support) and then reinstalled the older Acer-supported drivers. Sadly, it didn't make a blind bit of difference... but I still had to endure reinstalling apps again and customising the PC to the way I like it. At least all the data on D: was left alone so I didn't have to SyncToy it across from my main PC again.