I've built them for years, but the Dell in my sig is better than anything I could've built from parts for the same money (though I bought the drives and RAM from newegg). It's well designed, it looks great, it's quiet and very fast. You can't overclock it, but honestly this system is massive overkill for 90% of my needs anyway. And they threw in an extremely good 1905fp monitor as well.
Their mid-level servers are damned fine units.
I have a little Inspiron 700m on order, also very cheap for a Pentium M ultralight.
Plus they've started hiring Americans again - something that means a lot to me.