If your talking lowend Duron or low XP processor for surfer and casual "gamer" (windows games , tetris and the like) for office use then my personal recomendation is an 810 model from either pc chips or ecs...
http://www.z-buy.com/product.asp?item=mb-pc810
or this with non-upgradeable Duron 1300+
http://store.yahoo.com/newtech/pcchipm8witd.html
I have bought and setup several of these with no problems...my neice plays "Syberia" on hers with no lag or choppiness.
Others will warn you off, but I have had alot of luck with several of these!
The Biostar M7VIG pro is a higher end all-in-one solution.
http://www.newegg.com/app/viewproduc...fer=pricewatch
Just remember ....shared video = less ram / buy lots!
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I personally would look for something with at least 2 PCI slots and a 4x AGP....people hate it when you tell them they cannot upgrade next year! (sometimes a month later..."oh, I thought I would get more upgradeability for my $300 bucks!!)