amd x86 64 - mysql - winXP 32 - FC4 64

I'm currently running a rather large database (80g) on a winXP Pro box. It's a decent system with 2 striped sata raid channels, 2g of ram, and a amd64 939 socket 3200 processor.

When loading or refreshing large tables (locally using perl-mysql), the processor stays SPIKED for the duration.. memory barely takes a hit.

My question is.. would I see a significant performance increase (worth the effort of starting over from scratch) by scrapping the XP install in favor of Fedora Core 4 64bit ? By significant I mean 20-30% Or would hardware upgrades (to, say multiple processors) be the only option to reap that kind of benefit?

You should see some output improvement, just from the step to 64bit world. But it'll be real hard to say just how much in advance. Maybe you can back the system up, do some speed tests, upgrade to linux and run the tests again to see what improvements you make. If the cpu is spending time topped out while not touching peripherals or even memory because its number-crunching, then you may find the performance gains quite considerable.