If your going down the AMD route I can recommend the Asus A7N8X MB. This is the board I upgraded to just before Christmas, which even though I had few problems setting it up (mostly my fault) I haven't had a BSOD since it was up and running.
It will fully utilise all the new chips from AMD with its FSB333 and it has the new Nvidia2 chipset on board. I've got the deluxe version which has dual lan ports and a serial ATA connector for when I get round to using them.
Couple bits of advice if you do use this board:
Check your memory because as with most Asus boards this one runs on only unbuffered sticks.
Check the depth of your case - most modern boards with all their extra bells and whistles are that much deeper, and if you are not careful any connectors at the front edge of the board will fall foul of the 5.25 drive bay housing.
Check that your PSU has anough guts in it for the newer generation of board. Min 350 watts - ideally 400 plus.
Last thing is - it's best to set it up on clean install of your OS, and not an overlay like I tried to do. Boy- did I have problems
And No - I do not work for Asus. There is so much crud on the market which promises everything but fails to deliver, so that when I do find something that does work I feel I should pass the information on.
http://usa.asus.com/mb/socketa/a7n8x/overview.htm