Well, the question is this...what are you feeding the headphones with? In other words...is it the main outs? It could be the card itself that is being noise induced. I would n ot doubt that the system is not configured for noiseless operation as Dell does not configure systems for this...they are general home based or work based systems.
Where is the card seated and have you tried a different PCI slot?
Opus

could also be a combination of power source and power supply. You might consider upgrading the power supply (and holding on to the old one when you upgrade, that way you will already have a good power supply for your next machine). And possibly look into an UPS (not the brown truck that delivers things... that's pronounced "ooops")

i monitor from the headphone outs on the omni breakout box. the card is in the number one slot and i tried moving it but to no avail. i literally hear the cursor moving on the screen! or hear a program opening. this doesn't happen out of the onboard sound card only the 66/omni.

OH!!! Now that makes sense!!! If you hear the cursor move and other things like that than that's not audio card related. It's system related!!!
Here's some facts for ya! At work all our PC machines(ya know I'm sooooo tempted to write out Pee Cee's because of SOS and the gang! lmao!)
are Dell's. When I was testing the Apogee MiniMe's with Wavelab I would get cut outs everytime I moved the mouse...it happened on three different machines at work and they all were Dell's!! I tried it on my two machines at home and it did not do this!!!! So, this is a Dell issue! You can now take a sigh of relief and not worry about trashing your sound card! lol
I haven't chased it down as it only happens on Win2k or higher. What OS are you on? I bet it's Win2k or higher isn't it? If it's 98 I wouldn't doubt it happening as well as I think it's just some weird Dell config issue.
It could be the video card driver that Dell uses, it could be the BIOS needs flashing or something in the BIOS needs changing but I'm not sure what it could be in the long run. I have been meaning to try to chase it down but it's not high on my priority list if ya know what I mean!
So, at least that gives you an idea of what it is. How to solve it is another issue at hand. My first guess is to do some driver or BIOS updates
Opus :D

and I humbly suggest you move your soundcard out of slot one even if you don't notice a difference with your noise problem. Just a good habit to have...

thanks guys, i flashed the newest bios and am checking into the video driver. i appreciate the help...long live my delta!!!!

oh by the way i am running xp pro....you are correct, now i am impressed....esp