The 3800 Venice is more expensive than a 3700 Sandiego. The Venice core is a sandiego with less cache. The venice does not have more features than a Sandiego core. But when it comes to a cpu go with what ever you can afford, not by what someone tells you.
Athlon 64 3800+ 512K 90nm Rev. E...
Go with this board and you cant go wrong. Best Athlon 64 AGP board. It also has socket 939.
DFI UT NF3 ULTRA-D:
http://www.newegg.com/Product/Product.asp?Item=N82E16813136161&CMP=OTC-pr1c3watch&ATT=Motherboards