This might initially sound like an odd solution but, if it's a performance problem, you might be better of actually removing some of the memory. Windows 98SE was never designed to manage as much as 512Mb RAM - it runs best on 128Mb in most cases, though I've had Windows 98SE PCs running up to 256Mb when there were very memory-intensive applications installed such as AutoCAD. Remember that Windows 98SE is essentially an update of Windows 95 technology, which was released over 10 years ago when the minimum spec to run it was a 66MHz 486 processor and 16Mb RAM !!
I'm assuming that you're not getting any specific error messages?
If reducing the memory doesn't help, try uninstalling the USB wireless adaptor and see if it then runs OK.
Let us know if that helps or if you need further advice
