Thinking of getting a Dell refurb for the Mrs and some have 64 bit Windows Vista. Any advantages to it? Should I reinstall it with a 32-bit OS for compatibility reasons with software she'll tend to use (web stuff, pictures, etc)?

Take inventory of what you have and then decide. Some programs may not be compatible with Vista 64-bit and some devices may not have 64-bit drivers.

This article gets to the point very quickly:
Differences and Advantages Between 32-bit (x86) VS 64-bit (x64) Windows Vista

able to use more ram (4gb barrier) is the main advantage.

but if all you're using the PC for is web,pics, etc. you're not going to need that much ram. Downgrading to 32bit-OS would make more sense in terms of software compatibility.

sygate personal firewall doesnt work in xp 64 bit... I miss it so much considering going back to 32 =/

For normal users, you won't notice much difference. But applications that deals with very big #s or precise #s (i.e. cryptography), 64bit definitely speeds things up quite a bit cause what previously took 2 instructions to compute, will now only take 1 instruction.

32-bit OS it is!

Don't think Mrs can justify a 64-bit OS for her uses!

Thanks for the input!