Well my processor is AMD Anthalon 64 X2 Dual Core Processor 4400+ 2.3 GHZ

I have 2gb of ram.

My Graphics card is Nvidia Geforce 6150SEnforce 430.

What do you guys think i need to upgrade?

Your graphics card. get a Nvidia GeForce 9800 GT or ATI equivalent. They're cheap now (prolly about $100) and is all you need for SC2. I have one and run the game on all Ultra graphics settings. Mind you I have a quad core processor and 4 GB of RAM, but upgrading a processor is way harder than upgrading a graphics card, and your dual core is fine for SC2.

Edit: You could easily settle for less than a 9800 GT though if you don't care about having the graphic settings too high. Any Nvidia 7 or 8 series would work with the game and run it smooth on medium settings

thats great. will i be able to find this graphicsh card at best buy?

what about this graphics card?

Galaxy - NVIDIA GeForce 9500 GT 1GB DDR2 PCI Express Graphics Card

Its on sale at bestbuy

Depends... How much does it cost?

Don't buy a 9500gt! Seriously, that card is badly outdated.

It's much faster than your current onboard, but crappy unless it's just super cheap. Get a 8800gt or better. You should be able to easily find a card at that level for under $100.

See here for an idea of how fast specific cards are: http://www.scribd.com/doc/28004109/Graphics-Card-Hierarchy-Chart-March-2010

Get an HD 5670 because it doesn't require much from the power supply and its up to date with modern games/technology.

http://www.newegg.com/Product/Product.aspx?Item=N82E16814161334&cm_re=HD_5670-_-14-161-334-_-Product

Thats what would be good for your system, so long as you have a normal PC tower. Pretty much any PC can take one of these.

The HD 5670 is a good option, the HD 5750 is even better and you may find it almost for the same price.

If you want something cheaper, there are still plenty of cards better than the 9500 GT. I like this chart, it's similar to the one ameratsu posted but it's in text which is great for searching:

http://www.tomshardware.com/reviews/gaming-graphics-card-geforce-gtx-480,2598-6.html

Based on the OP's specs I assume he got his PC at Best Buy or some other store that sells them pre-built. If that's the case then he's using a 350 watt power supply so he can probably just go into Best Buy or another store and ask one of the employees to grab him the best card they have that can run on that power supply.

Unless of course he wants to get a new power supply too, in which case he's looking at another $100.

The card that WilliamWatts suggested only uses 64 watts, it should work even with a 350 W PSU no?