Advice Upgrade/Repair/Build System

I built a system 4 years ago and not only only is it time for an upgrade the system has also died. It fails to boot I think it is either a mobo or processor issue and it is essentially not cost effective to try and get replacements to diagnose. So I would like to build onto this system if possible. Essentially I am looking for a Mobo, Ram, Video Card build that will work within my current system. I am not much of an audio guy so onboard audio is fine by me. My current system is below.

The quick and dirty:

Primary use: Gaming

Budget: $300-$500 (if possible)

Current Build:

ASUS A8N-SLI Deluxe 939 NVIDIA nForce4 SLI ATX AMD Motherboard ~Suspected Dead~
AMD Athlon 64 X2 4200+ Manchester 2.2GHz Socket 939 89W Dual-Core Processor ~Suspected Dead~
CORSAIR XMS 2GB (2 x 1GB) 184-Pin DDR SDRAM DDR 400 (PC 3200) Dual Channel Kit
EVGA 01G-P2-N592-AX GeForce 7950GX2 1GB 512-bit GDDR3 PCI Express x16 SLI Support Dual GPU Video Card
Western Digital Caviar SE16 WD2500KS 250GB 7200 RPM SATA 3.0Gb/s 3.5" Hard Drive
BenQ 16X DVD±R DVD Burner With LightScribe Black E-IDE/ATAPI Model DW1655 LightScribe Support
APEVIA X-Navigator ATXA8NW-AL/500 Silver / Black Aluminum ATX Full Tower Computer Case 500W Power Supply

No need to worry about OS I have Win7 and I also have a monitor (1920x1080) and speakers.

I loved the above system it served me well for many years may she RIP!

Thanks to any all who read and help!

You didn't list CPU as a component you wanted to upgrade, but I will assume that you did want to upgrade it as you suspect that its non functional. With your budget it will be difficult to fit a quad core and a descent video card, so I had to skimp on the motherboard.

Asus P8P61 - Intel I5-2400 - $250
http://www.newegg.com/Product/Comb [...] mbo.631838
Ram - Corsair2x2gb 1333 - $45
http://www.newegg.com/Product/Prod [...] 6820145278
Video - two choices both under $210 Radeon 6870 1GB, GTX460 1GB
http://www.newegg.com/Product/Prod [...] 6814102909
http://www.newegg.com/Product/Prod [...] 6814130571

This puts you at $500 without shipping or any rebates. If you can spend another 40-50 there are much better board choices, this is the only one I could find that fit in your budget and allowed a good video card.

Ok Megamanx00, you seem to be missing the point. RXG26's current system is dead, he wants a gaming rig now, and his Budget is $300-$500.

I mean no disrespect, but aside from stating that he might need a new power supply the rest of your advice is horrible. It would be great if everyone could wait for a bulldozer, or if everyone could have a 2500k, or if everyone could save up for that 6990, but not everyone overclocks, and not everyone wants to wait, and not everyone has a $1500 budget.