Should I keep the 9800GT for the SLI?

Hello, here's my dilemma. My old computer died couple of days ago. (after a lot of testing it turns out it was a problem with the mobo and PSU, but I digress). What happened was initially I thought it was my video card, so without investigating first I went out and bought a rather noisy evga 9800GT.

So my old computer is not really worth salvaging. I'm now looking at building a new system (for about $800 Canadian). But I'm still stuck with the 9800GT. I can return it and get a newer card, but If I return it, the company will charge me 15% fee and I will lose about $20 to $25 dollars including RMA shipping cost.

Alternatively, I can buy another 9800Gt and SLI the new machine. But I nor any of my friends have ever used SLI before so I'm rather uncertain about it. Also, if I go this route I will need to mod the card so it is less noisy.

Any recommendations? Should I return the 9800GT, pay the $20 dollars fee, and buy a new video card, or get another 9800GT and SLI.

Thanks.