You can get a 4850 for cheaper:
Newegg.com - GIGABYTE GV-R485-512H-B Radeon HD 4850 512MB 256-bit GDDR3 PCI Express 2.0 x16 HDCP Ready CrossFire Supported Video Card - Desktop Graphics / Video Cards
it has approximately the same performance of the 9800 GTX+
As far as AMD boards go, this is a very good board:
Newegg.com - Foxconn A7DA-S AM2+/AM2 AMD 790GX HDMI ATX AMD Motherboard - AMD Motherboards
It's good for overclockability, and it's also pretty future proof.
It will run AM2+ and AM3 processors, includes the SB750 southbridge, with ACC for Phenom processors to increase overclockability
it also includes the worlds best onboard GPU (AMD 790GX). so if you're left without a video card for whatever reason, it has a half descent GPU for backup.
Otherwise, you could look at 780G boards, which are cheaper (but try and make sure it has a 5 phase power design) though they usually have less expansion slots.
There are also Nforce 570 and 590 boards which are good for X2's, though not all of them will support Phenom's (a BIOS update is sometimes needed, but sometimes manufacturers are too lazy to make one)