Sounds like, in addition to all your other driver issues, your computer is using the generic VGA driver rather than the chipset-specific driver it should be using. Whatever motherboard/driver media you have must be all wrong, or maybe the "installer" only dumps the driver files onto the PC but doesn't load them? Considering you have a Dell neither would surprise me.
I managed to get most of a re-installed Dell system operating normally a few years back by figuring out what chips/chipsets it was using (for the Ethernet, Display, Sound, etc.) and downloading various versions of the drivers from across the internet (not from Dell) until I found some that worked adequately. But it wasn't fun.
For hardware identification I did this...
1) Found the physical chips on the motherboard and searched the internet for the part numbers.
2) Booted Linux from a Live CD (I think the distro was Knoppix, but I don't remember), looked at various things in /proc, then ran hwinfo, dmesg, etc.
By the way, Linux automatically found drivers for everything except the USB-based wireless adapter (which wasn't being used anyway) - but I couldn't convince the person who owned the PC to switch from Windows to Linux.
