Only you can answer the question of whether or not to upgrade. If W2000 does everything you want, now and in the forseeable future, why change? There are only 2 possible reasons:

1. Enhanced security. Windows XP Pro is more secure than W2000 but most home users are unlikely to notice the difference.
2. The improved interface. It is more intuitive to use with better help. However, if you are already familiar with W2000, learning a new approach will initially slow you down.

The arguments for not upgrading are:

1. Very occasionally Windows XP is a dog to install. Look at the MS forums, some systems don't like XP and it causes the users a nightmare. There seems no way to tell whether your system will fall into this category.
2. Support for older hardware. If you have anything running through the parallel port (apart from a printer) it is unlikely it will work under XP. This includes scanners, force feedback steering wheels etc.
3. It uses more resources and so unless you have a modern (>1GHz) machine, it will be slower under XP.

If you want to try it and see, use Partition Magic and install as a second operating system. Dual boot for a while and once you have reached a decision on what to use, take the losing operating system off your machine.