5.1 Surround sound speakers with no sound on the front left or right speakers.

I don't know hardly where to start: I have a dell XPS 400 desktop computer I bought with 5.1 speaker setup, with a Creative Sound Blaster X-Fi soundcard from the time I got the computer the sound worked fine. After about a year because of system problems I had do a format of the harddrive and reinstall windows XP Pro and all my other software, everything worked fine except for the sound. At first it was no sound but I fixed that right away now I have sound but nothing from the front L & R speakers I also have an error with my IDT High Definition Audio Codec - Code 10 can not start. Can't seem to get that fixed no matter what I do There is a lot of stuff online about this problem and I've tried alot of the fixes but nothing works Most of the time all you do is knock out your sound all together and have to spend a lot of time to get back to where you were in the begining. I was told I needing to download a driver from dell Sigmatel driver STAC 92XX C-Major HD Audio 5.10.0.4823.A05 which I did and at first I thought it worked, I did have sound in my front left and right speakers but lost the sound in all the other speakers tried a number of things to fix but nothing worked so I uninstalled the Sigmatel driver and went back to what I had. I also downloaded any updated drivers for my soundcard they had from Creative.coms website and still have same problem anyway my front two speakers work fine I just can't get them all too work together. I've tried many more things than I can list here, my head hirts just thinking about it I believe this is not a hardware problem but a software problem which someone out must know how to fix. Any help would be great!!!  Thanks