Yeah I suppose, but why not use 64-bit anyway? The mixed market isn't helping anyone. Yeah there's the hardware that the cheap-ass companies can't bother to support (like my HP Scanjet 4400C), but 64-bit is the future, not 32-bit. Plenty of hardware isn't supported in Vista 32-bit either. Supporting, what, 4 Windows OS's isn't making driver development simpler, that's for sure.
If you are building a new machine, I just don't see the sense in blowing at least $100 on 32-bit Vista.
I solve my scanner driver issue by having two comps at home. One is the gaming rig with all the newest stuff that's off most of the time, and the other is a always-on low-power-use machine with good 'ol XP 32-bit on it. I find it ironic that my HP Laserjet 4P from 1993 still works in Vista 64-bit, while my HP scanner from 2001 does not. HP PCL5 print drivers FTW.