Ok first off .. and <b>unbiasedly </b>towards any OS that you have, you have to check your installation of Win2k. Although the boot time for Win2K maybe slow, it is quite nimble once you configure it properly. Checking it would include to see if you have any hardware issues .. what services and programs you have running at startup and what is infact the root cause of your computer being drained of its speed (seeing how you have a machine that is more than top notch).
Having said that, yeah Linux will make your computer seem faster than with any Windoze OS out there. Not only is Linux very well crafted, it eeks out every ounce of juice in there, it is not a generic installation like Windows. You can even optimize the Linux kernel to run with your particular processor in mind. While you have only let us know as to the specs wrt. RAM & Processor, to do a good check of your hardware, you need to go to the homepage of the Linux distribution you are planning on using (I'd suggest <A HREF="http://www.mandrake.com/" TARGET="_new">Mandrake</A> for a desktop installation) and check for hardware compatibility .. or post here with detailed specs such as motherboard, video card, modem, snd card, NIC etc etc.
The last thing is, you have to know what you are doing with a UNIX/Linux, it is very easy to learn it all. If this is your first time at one of these then I'd suggest picking up a book (usually good books come with a distribution of Linux free).
HTH