I use msstyles Halcyon - attached is a grab of my XP taskbar. You can change this tioblue/green/grey etc.
I'll be happy to upload the style for you, it's the best I've seen and I spent a long time trying to find a good one.
It basically turns XP into a Vista lookalike without having Window Blinds running or anything.
As
nicke261192 says, you do need to patch that .dll but it's a doddle to do.
THIS is the tutorial I used (includes already patched files).
Let me know if you'd like it - it's about 17mb.
:edit: it's actually compressed to just over 3mb which is surprising..