Early last year, I bought a Dell for my wife - purely because I couldn't get a build to match the specs of the Dell for any cheaper. Including the 19" LCD, it was only $500 - it's a 3ghz Pentium D with 2gb ram, 80gb hdd, dvd burner, XP home etc. I could have built a similar machine for about the same price, but the 19" LCD really pushed it over the edge and she needed a monitor with it too (BTW, the Dell LCD's are *really* nice).
She does some image editing stuff for scrapbooking and web surfing and the machine has worked perfectly for her. I think that for a low-medium end computers to be used by non-techie type folks, prebuilt systems like Dells are the way to go. Of the 4 people I know with Dells, only one is having trouble which is actually related to Vista usability (my mom is having a difficult time making the switch from XP) rather than Dell quality.
Would I ever buy a Dell for myself? Nope. Would I reccomend one to a non-technical friend who just wants a cheap computer that's ready to go with no monkeying around or OC'ing? Yeap.
Well, I guess I technically use a Dell myself...but I didn't buy it - it's a company issued laptop for work. I'm on my 2nd one now (just got upgraded to a C2D machine
) and haven't had any problems with either.