The college I went to up until last year used nothing but Dells in all the computer labs. What a nightmare.
They all always seem to RUN, but they ALL have input device problems. We had these P3s in the one lab, and you'd get halfway through class and the keyboard and mice would fail on about half the machines. New mice and keyboards didn't help, and they locked up if you plugged most USB devices. All you could do is sit there and look at your inaccessible work.
The PIV and Core 2 Insipirons all had major USB port problems. For one thing, they pointed at the ground at a 45 degree angle, and only detected USB thumbdrives about half the time. Sometimes, plugging anything in would lead to an instant reboot.
The Core 2 Inspirons were the worst, because they didn't have have PS/2 ports. For some reason, unless you plugged the keyboard and mice into the top two slots on the motherboards, they didn't work. Even then, it usually took several reboots after unplugging them. It took us hours to get them all to work when we moved them to set up for a programming contest.
When someone comes into an IRC channel and moans about USB Port issues, I usually respond "What Model Dell?" The reply is usually Inspiron.
I had to repair a PIV Inspiron once, but I had to ask for the keyboard for it because none of the USB keyboards I had would work and it didn't have PS/2 ports. Its kind of embarrassing.