It depends on how far you take it... Lemme break it down...+++Assuming you want to modernize it, run the latest OS, and play newer games: If it's running windows 98, your motherboard and powersupply are most likely out of date. The CPU will need replacing. The ram will be too small and won't be the same type your new motherboard needs anyway. If you've got a working CD rom, you might still need to upgrade to DVD in order to install Vista (or some other games or OS's). In short, the whole computer needs replacement. Your cheapest option is to buy a (used) newer one or a new budget model from the store. You may even consider selling your older computer to someone who just wants it for email/kids or to someone who likes to play vintage games (either emulated arcade or native-era PC games).+++Assuming you just want to improve a certain spec to play some Windows 98 product or to get it to run XP: At this point, you may have to resort to EBay or a computer liquidation house for parts. Your local computer store may not carry ram to fit it, for example. Still, without knowing how bad, I'm guessing that you can update it enough to notice an improvement and open up a few options... but probably not enough to play any modern games.+++Final thought: Consider getting a lightweight linux distro and trying it. If you're not into games or a lot of multimedia, this is the option that is cheapest AND the easeist. http://distrowatch.com/ This is your starting point.