Of course. It is simply a matter of disabling all the new features XP has, including system restore. Windows 2000 being called "fast" is relative. It is slow as molasis during boot-up. Windows XP is actually designed to improve application load speeds over time. Running it on a K6/2 doesn't make any difference.
Besides the smoke and mirrors, show me a typical K6/2 system booting up faster then 2k, even just a few seconds! Personally, I don't care about boot time, if it takes 2 min vs 20 seconds, SO WHAT! What counts is real system performance. It's plain and simple: XP was designed for later CPU models, where 2k and before was released at a time where CPU's like the K6/2's were king. Since XP was basically optimized for later CPU models, performance differs quite differently on older CPU designs vs new CPU designs. Did you even try XP on a K6/2? I know I did on a couple, and no matter much useless garbage I disabled, they were never good enough to be comfortable to use long term. Bottom line: Even through the underlying kernel is only a mere .1 version difference, there is still a lot more above the kernel level on XP than 2k to make it use more resources no matter how many "features" you disable, many of which resource users are optimized for late model CPU's.
My experience is this, on typical K6/2 machines, Fully loaded Windows 98, 2k, and XP - boot time is about the same, or just about two minutes from the time I push the power button, until the desktop shows, and the hard drive activity settles down. "Fully loaded" means in the real world the systems are complete with lots of device drivers. If you take a fresh out of the box XP, sure it'll boot fastest of all. Video and CPU performance wise, 2k performs slightly faster than Windows 98, and XP was considerably slower - too slow to be comfortably used. Tweak and disable all my might, but still not fast enough. Keeping that these were K6/2 CPU's and total performance would be far different on a later model CPU.
I have to conclude you are just basically repeating MS's marketing statements, and/or believing what other inexperienced people say, and have no experience other than that new 2Ghz+ computer that came with XP.
So to the OP ddare0, I have real experience with your type of machine. XP just won't cut it no matter how many XP- baised people tell you how good XP is. You'll be very happy with 2000, which is still a HUGE upgrade from 98.