I have been using V5 manufacturing for about 2 years now. Yes, It takes a while to setup the info required, but once you are there, you will save bags of time. No doubt, when you used NCG this had to be done as well. Try using R10 SP3??
I have run Catia on a P3 with only 8Mb Video on board. It worked fine. Drafting however does use alot more resources of your machine. R10 should solve alot of performance issues, but as for crashing?????? Have you unistalled and reinstalled Catia? Is there any other software that is using system...