Upgrading Graphics Card Options

420W PSU might be a bit thin depending on quality. I'd start w/ a budget in mind and then looking at this:

http://www.tomshardware.com/reviews/best-graphics-card,...

With an SLI board, you have more choices w/ nvidia .... for example, where that article points to a tie between the 4870, 260 and the 5770 at the $155 price point ..... the same three way option isn't available to you at $310.

The question then becomes, do I buy with the thought of not buying more card than is appropriate for the system or with the thought of taking this this card / PSU to another box in a future build ?

For 1920 x 1200, the entry point is the $125 range where a 4870 512 MB is listed in the article at $125 ....yeah right   .... they start at $180 on newegg. So now we're back up to that $155 price point which really means $175-180 for the 260/4870/5770.

But now we have to consider PSU issues .... w/ 2 GTX 260's ... using the calculator linked below I came up with 452 watts which, with a 20% cushion, would call for a about a 550 watter.....but that would put your GFX subsytem far above the rest of the box. With just one, your old PSU should hold up if it's half way decent.

http://www.antec.outervision.com/PSUEngine

Now that 260's an 11 tier jump according to the link below and even a single card will be bottlenecked by the CPU and rest of the system

http://www.tomshardware.com/reviews/best-graphics-card,...

Dropping down a notch puts you into 4770 / 9800 GTX / GTS 250 category

http://www.newegg.com/Product/Product.aspx?Item=N82E168...

Still more GFX card than is needed to match system specs but at least it can be carried forward into a new system as a dedicated PhysX card.

If ya thinking PSU, the Corsair 450Vx / 550VX / 650TX / 750TX / 850TX right now are running $54 / $69 / $89 / $99 / $109