Processor for Shuttle Form Factor Box

I'm building a PC for my mom and am thinking of using one of the shuttle form factor barebones kits, but am unsure of what CPU to use.

Use of the machine:

Windows 7 Home Premium - with full Aero - 32bit as it will have 4GB of ram.
Minor Excel/Word work
Basic photo editing - red eye removal, cropping
Web
Email
I'd prefer it to be relatively quiet.

I'd also like it to do 1080P video, but 720P would be ok too.

The Shuttle SA76G2 is an AM2+/AM3 wiht ATI RV610 Graphics

Processors I think might work:

45W:
Athlon II X3 400E
Athlon II X3 405E
Athlon II X4 600E

95W:
Phenom II 945 Quad

Is the Phenom II overkill for her needs, are the Athlon II's fast enough that she won't think it's slow (currently using an old Core2 in a laptop).

Would an Intel based Shuttle Box be a better bet?

thanks,

Cryo