9800gt

no. it doesnt matter.

right now id seriously recommend just getting a new card like a gtx660ti or a 7850-7870 video card. you will get way more performance and more value than getting another weak card to throw in your system

I don't look down on that card unlike "TheBigTroll" as nvidia's low end can't even compete with this card lol. I suggest that you look at a 7770 if you are wanting to be cheap but also not have to worry about the power supply. If you want something much more powerful then I would go for a 78x0 series. Don't get to excited about the GTX6xx series as there are some quality and software issues at this time with those cards.

HD 7770 would be a trivial upgrade. Plus, money inefficient.

As for going SLI: if you can get another card cheap (like below $50), it's a really good idea to boost your system gaming performance. In SLI the performance will be close to GTX 560, which costs $160-170 today.

9800GT sli will suck a lot of power.

Go for Single Solution.

Not the 55nm models

i have weighed all the info you guys have given me and i am getting a gigabyte gtx660ti 2gb. i am also getting a 1000w power supply   , just in case i get another one down the road  

you only need a 650w. 1000w is overkill and is suitable for 3 way SLI which you cant do on a regular board