AM2 is the platform of choice for current AMD hardware. Socket 939 is classed as legacy hardware. AM2 gets you DDR2 instead of DDR (no particular benefit at the moment) and the dim possibility that you might replace a AM2/3800 with some faster AM2 chip at a later date.
64 bits doesn't really get you much of anything in Windows or in Linux, but in Linux there's no particular harm in using it, either.
An Athlon64 3800 smokes most everything Intel has in the single-core world, particularly for the price.
Dual core is generally a happy thing, but a dual core "3800" is generally slower for any single operation than a single-core "3800". 99% of the time, no one will notice when a single-core is faster than a dual core chip, but it's really easy to see the times a dual core chip is faster.
SATA drives are cheaper because more new drives are made these days with SATA interfaces than with PATA. Depending on the hardware involved, loading Windows can be somewhat more difficult on a SATA drive.
My low-end motherboard of choice at the moment is a Gigabyte GA-K8N51GMF (or the AM2-based GA-M51GM-SG2). Both use the nVidia 6100 chipset. I've loaded SuSE 10 on one, one time. SuSE did not detect or load a NIC driver; I believe this has something to do with a licensing issue with an nVidia binary-only driver, rather than a failing on the part of Linux.
I really prefer SuSE to Ubuntu.
And I *don't* think Windows is the best choice for a home user. I think spyware and all the outright SHIT that home users have to put up with: Antivirus updates, junk applications, WGA, Microsoft not releasing security updates in anything like a timely fashion, Internet Explorer... Those are all very compelling reasons not to bother when all someone wants is the ability to browse the web, get e-mail, listen to music, store photos from a camera and maybe type up the odd document, and Linux does all those things really well.
I've found that about 75% of my non-professional track students have never, ever made a folder or copied a file out of its default location. I have a really hard time believing those are people who need 100% compatibility with Microsoft Office.
Recommending Dell isn't doing a home user any favors, either, since people actually expect support when they buy a computer. I bet every single SF.net regular has had to help someone with a Dell after that person tried to call Dell's support.
