Windows 98SE Lock-up

I have a problem with Win98SE locking up when I am in IE5 I have changed to IE5.5 dod not get any better or any worse. this also occurs when I am using multiple Office 2000 windows and using my scanner and trying to copy from scanner program to wordI have used office repair this is not the problem I have noticed that keeping the IE temp file clean does help as well as shuting down all unneeded programs from task manager. it also help if the system is freshly booted when it locks up all I can do is con,alt,del 1 time wait a minute then repeat and the system reboots without scan disk running, any other keys will totally lock the system and require a reset which brings up scan disk I have tried removing programs as wellas reloading the os after reformatting c:/ drive. when this was first built i did not have this problem until i lost a hdd and changed the raid card to use 2 30 gig hdd's to back-up date so I can rebuild a drive if needed. the system is a asus a7v with a AMD 1200 T-Bird 512mg. of pc133 sdram any idea's short of loading win2k or XP pro.? I have both os's and have been thinking about a fresh install of one or the other?