Your teacher is an idiot.
What's worse, in my estimation, is that he is a professor (which I always equate with a higher education. We are talking PhD here). A few points I want to address.
he likes Windows 2000 better than XP because it is more secure, has fewer problems, and you have more freedom in WIN 2000.
What, what, and what? The core OS is probably less secure, as it is older and does not have the benefits of newer patches/fixes that the core XP has (core = default, fresh install, no patches no SP). In terms of problems, I find I have no problems with either. I'll call it a draw. More freedom to do and for what? I can run any software on either OS. I can do whatever I want with my PC regardless of OS (I can probably do more with XP, actually). The only "freedom" issue I can see differenbtiating the two is XPs product activation. If that is the professor's complaint, he should not be using any MS (or anyone else's software) if he doesn't like their EULAs.
He told me the only difference between 2000 and XP is that XP has a new interface and more built in after market software.
I find it curious and, frankly, ignorrant, that he contradicts himself here. First he goes on about how 2000 is more secure, more freedom, yadda yadda, then he says that the OS is the same. Which is it?
2000 is just as fast and more reliable on modern hardware and better for gaming for modern games than XP.
2000 and XP are about the same speed on the same hardware. Except at boot, where XP blows 2000 out of the water. (Average XP boot time: 15-20 seconds. 2000 boot time: 45-60 seconds. Same hardware. Another contradiction too... If they are the same OS, how is 2000 "more reliable" on modern hardware. Especially since newer hardware will be supported better in the newer OS. In terms of modern gaming, at least, he is correct. There will be no real difference.
Do you think I should give 2000 a try based on what my professor said, or stick with XP Pro?
I'd have a hard time, granted it's based on this one comment, listening to any advice or information from that professor. And, if you want HT enabled, XP is the way to go. If you don't like XP's interface, simply disable it. Some things your professor said are true. In real terms, the OSes are nearly the same, once completely patched. Windows XP offers some benefits, like increased "official" hardware support (though I have not come across any hardware 2000 couldn't use, but my hardware needs are pretty vanilla), more "offcial" driver support (however, most drivers are now written to be "2000/XP compliant" so you are safe either way in most cases), faster boot times than 2000 can acheive, the aforementioned HT support. Both are excellent OSes. Both are incredibally stable. The only BSOD errors I have gotten with either were results of my own tinkering, and not the fault of the OS. The bottom line, is that your professor is a fanatic for one OS over the other, or is grossly misinformed and both a victim and perpetrator of FUD.
\Dan