If you look around more and more places are asking for stock computers with Windows XP on them cause too many people don't want Vista...so they are out there...I think Circuit City has XP machines, but BB doesn't?
I have a Toshiba laptop and for low end web wheeler type computer it works great and it was cheap...<$500 new.
Sony's are always good, but they are towards the higher end of the price range. Dell has fallen off the quality they used to be IMO, but it seems that Gateway has actually been getting decent reviews the past 2 years or so. For a while there they were complete crap.
Compaq bought HP or the other way around, can't remember...the HP's have gotten decent reviews, but their association with Compaq scares me...Compaq has a reputation for using very crappy bus' and always seem to tend towards crashing...
I think they exist only to create entropy in the universe...very irreversible types.
Other ones I don't know too much about. I have seen some good reviews of Acer stuff...I think they are like the Hyundai of computers and might finally be getting to the point that it isn't embarrassing to own one.
I would use your friend Google and SEARCH!