I think it is more likely the dell drivers. They may not be 7 ready.
Yes, the vista ones should work, but there is no telling what dell does to the drivers.
I would, go to the manufacturers of the hardware, if its Intel board, I would try the intel chipset and NIC drivers off of intel's site for vista or 7, then find video and audio model numbers and go to those sites and try to find something close to match.
Long time ago,, the Nvidia 4GO card on the Dell Inspiron 8000 series worked better with the 400MX drivers from nvidia's site than dell's drivers did.
If it's AMD, then it may be that the combination of hardware and drivers that dell has put together just isn't ready for 7, it is a very good possibility. For the AMD, try the NIC drivers from
here .