Oh yeah, all these laptops and desktops become junk after about 3-4 years. Now if its a big piece of junk like a 17 inch laptop or a desktop, then it becomes essentially a paperweight. However, if its a 14-15 inch piece of junk then its still useful because you can tote it around as a web surfing machine. I would not get a desktop, but instead a 14-15 inch machine. Sandy Bridge processors (soon to be Ivy Bridge) give them a lot more power and are more then what you need to trade with from day to day.
The Thinkpad brand that IBM sold to Lenovo is very good in terms of performance and build quality. I have an 13-yrs old one and an 2-yrs E420, which are both working today. Highly recommended. I have some problems with Dell notebooks both at home and at offices (slow to boot, some keys fall off after 1.5 yrs).
I'm picking up this old dog to let you all know that I chose these guys: http://www.santech.it/shop/default.aspx and so far, so good. If any of you would like to know more, I will post a brief review.