Opinion On Upgrade

Im looking for some feedback on what i should get in a upgrade. Something that can play recent and upcoming games such as Fallout 3 and Dead Space. I have two computers, one of which im looking to upgrade. My current setup is as follows:

P4 1.7GHz
1GB of RAM
ATI Radeon 9550 256MB
250GB HDD

Now, i know this is basicly me building a whole new computer, but ill be using the power supply and tower for the new build. I have done some looking around and saw what i thought was some decent gear, however im not sure what it can handle in the gaming depot. Im not really looking for a super high-end rig, just something that can allow me to play recent games at a decent price.

GeForce 9800 GT Hybrid Power 512MB
AMD Phenom 9600 Agena 2.3GHz Quad-Core
MSI K9N6PGM2-V AM2 NVIDIA GeForce 6100 Micro ATX AMD Motherboard
2x 2GB DDR2 800 RAM (4GB)

At most of my local computer stores, all of this can be purchased for about $400
If there is any better video cards and Cpus at a reasonable price, please share, id really apperciate it!

Thank you =)Opinion On Upgrade
You're better off buying an Intel processor. They out-perform AMD in almost every benchmark these days.Also an ATI 3870x2 or 4850 (depending on how much you want to spend) would give you even better performance. Opinion On Upgrade
E7300 or 85/8600 or Q6600, also that chipset is outdated. Integrated graphics for AMD cpus = AMD 740/780G chipset. IG for Intel = Nvidia 7*00.