Greendog,
I posted about my specifics here:
http://www.elitetrader.com/vb/showthread.php?s=&postid=78984&highlight=supermicro#post78984
Notice that I have the P4DCE. Today, they have versions of the P4 Xeons Motherboard with Dual Interleaved Memory - that is WAY faster - get that instead if you can afford it. The only "downside" is that you MUST use ECC ram with these. BTW, if you get a very high performace motherboard like this, make sure you get Samsung memory - there are a lot of resellers of Samsung, but you can always tell because Samsung imprints the website on the outside of the chips, no matter the reseller.
As to where I bought it, I bought the parts seperately so I could get the best price, eBay and other Internet sites (you can get the Matrox cards there very inexpensively, as well as the CPU's. NOTE WELL: if you get Dual Xeons, make sure the CPU's are MATCHED!) Since I know how to put these computers together, that was not an issue for me. However, check the SuperMicro website on where to buy if you would prefer that an outfit put it together - I live in Chicago and I can tell you that ICC is terrific (check under Central.)
And as I state in the link to the post above, I use Win2K - I try to keep up to date with all service packs.
The monitors I bought at eCOST and CDW. Check the link above to see the link to CDW, a decent online store.
nitro