Office XP- Outlook “not responding”

New Pent4 mach 1G ddr ram OEM install of XP. i installed Office XP Small Business (3rd application installed)within 48 hrs Outlook started “application not responding” soulution was close app and restart app. It worked for 15min-2hrs then happen again. I installed SP 1 & 2 and NOW IT HANGS EVERY TIME YOU TRY TO DO ANYTHING!! Since this is the PRIME machine my CFO (and wife!!!!) uses, there is of course NO PRESSURE. I have moved her to Outlook Express but that don’t solve the Outlook problem, just avoids it… any help to a marginally tech competent CIO would be appreciated.