Windows 7 is easier to use if you're using the 32 bit flavor. Finding the proper drivers for the Warp in a 64 bit environment was very difficult, for me at least. The steps are pretty much the same, though, for Windows 7 and XP alike:
1: Install the proper XP drivers. I did this by installing PDANet, which contains the appropriate drivers for many phones, right out of the box.
2: Download the one click root for Warp - "Ultimate Warp Drive" by SnakeX
3: Run the file called "- RUN ME - root + cwm + patch + stock.bat". Depending on your Windows settings, the file you see may not have the extension on the end of it (e.g. won't end in ".bat") but that's okay. Run it anyway.
4: Choose option #1 "Root + ClockworkMod + data patch" to install Clockwork, root your phone and install the data restore patch so that your backups restore properly.
5: Enjoy root access!
After this, you should make a backup of your phone as it is in its initial state... before you go buck nutty removing things like I did when I first got root on my I1
Also keep in mind that, down the road, if you restore a ROM image from a phone which did not have the data patch, it will remove the effects of the data patch on your device, and you'll need to re-run "- RUN ME - root + cwm + patch + stock.bat" and pick option #3 "Install recovery data patch (allows apps and data to restore properly)" to make things restore properly again.
Edit:
(Also can you explain how to roam on Verizon towers when rooted)
This apparently (at least in my experience) is not an option anymore, but is included in some PRLs from the days when Sprint leased access on certain Verizon towers. Some PRLs are still floating around the interwebs which do successfully place you on Verizon's service when roaming, but since the two companies no longer collaborate, Verizon prompts you to enter credit card information to continue with the call. Bummer.