Back to the OP's question and concerns.
Win98 is going EOL at Microsoft. SO WHAT!!!!!
If it still works fine with all you need this computer to do, keep on using it as long as it lasts, even spend little bits of money to replace things if they break (power supply, mouse, keyboard, monitor) Shop around, used items, especially for monitors can be quite good and quite cheap. Power supplies, Rodents, and Keyboards are cheap.
When it breaks big time, i.e. hard drive fails, processor fails, burns up...... Then go see what the market is offering and make your decision.
Right now, if you go buy a machine from Dell, HP/Compaq,e-machines, Sony..... they call come with WinXp (home or Pro). In 6 months to a year, they will all come with Vista.
End of Life is a meaningless term. All it means is that if you call Microsoft Support, they will refuse to answer your questions. If you find a bug (bloody unlikely), they will accept your information, but nothing will ever happen. EOL does NOT mean that Win98 will STOP working, that the machine will refuse to boot Win98. Far from it.
IBM stopped supporting OS/2 several years ago. There are tens of thousands of computers around the world (even ATMs, bank teller terminals, stock brokerage terminals) that are still going strong with that old product. Just don't call IBM for support issues with OS/2, you'll get no answers.
EOL does not mean that the product stops working, it just means you are on your own for support (and most of us are in exactly that shape regardless of whether we use something from Microsoft, a Linux version, OS/2, Apple........)