Its been out for 3 years and you have never read about what it offers and what it can do? Sit down at the internet and read up. Microsoft will release a new OS every 4-5 years but they support up to 2 versions back. If you include 2000 and ME then guess what, 98 is too old. Using more resources doesn't automatically make it better, it uses more resources BECAUSE it is better.
Not being suported by Microsoft is a huge deal. If there are issues with the game under 98, Microsoft wont provide support. If a certain 98 driver is causing issues, Microsoft again will not work with providers to fix the issues. You have to build for the latest thing out there and leave the old stuff behind. Its called progression.
Eventually you just have to upgrade. An OS isn't something like pixel shading 2.0 or 3.0, or the latest bump mapping code. Its the guts of what runs our software. Eventually things are tailored to use the best thing out there and currently XP is it.
AMD 2700+ XP
ASUS A7N8X Deluxe MB
1 Gig PC2700
Radeon 9700 Pro 128
Onboard Nforce2 Dolby 5.1 audio
2x WD 80 Gig HDs
Sony 52x CD / Plextor 12x/10x/32x Burner