If your PC is ONLY 6 years old, you may well be able to add memory quite cheaply. Mine is ten years old, and memory for it has become a but like gold dust. I could upgrade to 1GByte (max), but it would be almost as expensive as switching to a new motherboard with 2GBytes!
If you can dig out manufacturer/model for your machine, you should be able to look up the price of extra RAM.
Also, if you are serious about getting a new machine... what are you running on your old one? With Windows, some things are easy to transfer/reinstall, or will be coming as part of the new package, but some you may need to to buy again. (Unless you switch to Linux, and get everything free, that is... but I suspect you're not up for that.)
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"Striking up conversations with strangers is an autistic person's version of extreme sports."
Kamran Nazeer