I would recommend assembled and branded like Dell, because the service is good in case there is a problem. I had an IBM which was user friendly but I spend like$3000 on it an it was not compatible to the recent computers. So, then after 1years of use, it was trash. Then I got a compaq laptop, well I used it for about 2yrs but again upgrade issues there isn’t much room for that. Not to mention I started having hardware issues too and I could not find service rep that could help me order the part. All I needed was the fan and it took me an entire days of being transfered on phone and explaining part and issue to every rep I got hold of. Anyways, so, now I have a Dell, I got the latest one and got it built. There is lot of room for upgrade. I can add more REM, video card etc to it .according to my research, it should last about 5 years or more.
So, I would recommend buying an assembled computer Dell if possible. Get the with XP environment. Rest should be easy if you have service plan.
Let me know if you need help or more information.
Take care