Buying a New PC

I am going to buy a cheap (around 10 man) PC this weekend. This is really for Takechan to do his auction work and not bother me when I am using my main PC. Even so, I still think I need yet another PC to do OFF-Shore rendering of Movies I do. I can not game and render at the same time. For this PC all I need to do is access the Internet, Office Word, Load and manage pictures. I do not need it for music, movies or gaming so the specs can be way lower. I should get at least a 17inch but hopefully 21 inch screen. The question is should I make it or buy a packaged PC by a maker? I will go to Akihabara and check it out. One more note, I was really planning to buy this PC next year buy I need it now.