We would not recommend it for that old of a system. You would be better off either putting money into a new custom built system or into a more current refurbished system.
Only replace if it isn't meeting your current needs. You can try reinstalling your OS, if you know what you are doing, to get it to run more like it did when it was new. If you format and reinstall you will need to backup anything you can't replace by just reinstalling the software you use (such as documents, pictures, and any other locally saved data). But you would need someone to assist you who is very familiar with the process. Another option would be to get a new hard drive and put a fresh install on it, and then just hook up your old drive to keep or copy over the old contents you still wish to keep.
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