This is one area in which I firmly believe XP has the edge over OS X.
In XP, I just right click the entire hard drive (C, D, whichever it's labeled) and go to "Sharing..." and Enable Sharing Across the Network. Then, on your Mac, from the desktop hit Cmnd + K, and you can mount that shared HD on your Mac's desktop & browse as you please. (Assuming you've enabled Windows File Sharing in the System Preferences)
Now, on the Mac, it's more difficult. There's a folder called "Public" and anything in that folder can be seen across the network, but anything OUTSIDE of that folder CANNOT be seen. Pretty dumb in my opinion...yeah, in workplaces I see the security stuff, but geez. So basically anything you want your Win machine to pull over, you've gotta put it in that folder first to be seen.