what do you think hyperthreading is doing?
keep it if you like, but it does NOTHING for your realtime audio. how can a virtual core do a calculation without using a real core?
hyperthreading can give better benchmarks, but it doesn't necessarily do anything for the actual apps you are using. of course, your milage may vary, as they say in automobile television commercials here. it depends on how you use the machine whether this matters at all.
you know, i got a used core2 duo machine for $100 with 4 gb of memory from ebay. that machine had an nvidia quadro video card too!(the video card is a 4 head unit worth more than the computer) it was an office machine that had been decommissioned. it would work better than the computer you're currently using. you don't have to spend a tremendous amount of money to get your kid out of your music computer.
btw-i doubt if the video card is a problem. check the irqs and if the Scope card is sharing an irq with something, tell me what...