Spend the money or leave it in the box...

I have an old emachines T6212 that has developed some kind of problem with its motherboard. My computer guru says he needs to re-install the drivers. I have no idea why but if he says it needs x, y, or z, I pay for it. The problem is that I can't get into Properties. I also want to drop in an AMD 4000+ chip and an eVGA 8800GTS just like my present system has. I have no idea how much this will cost, but I am thinking I want to do it to have a machine set aside for FS9 only. I will run all my add-on sceneries, et cetara. The old machine currently has a 3800+ and an eVGA 7900GS-KO card in it, 3 GB of 400MHz RAM and a 500-watt p/s. It ran FS2004 pretty well, but not as good as my present set-up. I'm asking "Is it worth it?" Some of you will say No; others may say Yes. I'm looking for advice, here. And Thanks to all for any replies...