You don't state what you are running now or what you would like the upgraded system to be able to handle. For example, do you play a lot of games, do photo editing, or just want a basic system for surfing the net and home office uses?
If you upgrade the motherboard, cpu, case, ram and power supply, how is that not a new system or darn near it?
For example, you could look on Extremetech's $800 build it yourself gaming system and then pick which parts to upgrade to fit your budget and wants.
I'm looking to upgrade my current system, but i only have $1,400 available to complete the task. I'm looking to upgrade the basics if i can get away with it for now. example the cpu, motherboard, ram, case, and power supply. i am running a agp graphics card right now as well, and if figure i might have to upgrade that as well. Plus i also want to stick with windows xp if i can, i realize that i will have to buy a new copy xp when doing this, and so that cost i have factored out. so the remaining amount is the above number. if someone could help me out that would be great. thanks.