Needing advice on some upgrades on an older mainboard!?

have an ASRock K8upgrade NF3 board. It is a 754 socket that is able to go up to an AM2 socket buy a daughter card in the yellow slot. The AM2 add on card supports 8gigs of PC6400 ram and a max CPU of and AMD athlon64 X2 6000 ( the 95 watt version of the X2 6000). Also since my 7800 GS really can't hold up to newer games I'm wanting to play so I was going to add a 3850 by ATI. The 3850 is an AGP setup. I want to do this so I can upgrade the cheap way. Would this be a good investment or not. Thanks.