I'm pretty sure it's the wireless adapter on the XP machine or possibly my router but I was getting abysmal speeds transferring over wifi. Even after screwing around the best I could get is 1/MB a second and with almost 100 hundred GB's to transfer it was going to take 2 days. The first attempt was 200KB/s and would have taken a week.
The strange thing is internet speeds are faster. I could have uploaded to my server and then downloaded them faster. If you're getting real slow speeds over wifi use the Ethernet cable.
As already noted right click the folder in XP and select share this folder. Just plug the Ethernet cable into both machines. I had an issue where the network was being recognized but the machine itself wasn't showing up in My Computer, open "Network and sharing center". There should be a listing for unidentified Network, click the link next to it "Local Area Connection". Now click the diagnose button. Once it does it's thing the XP machine should be viewable in My Computer.
I was getting speeds of up to 60MB/s with Ethernet with large files, and that's nearly the max. Even a 1 hour DV file should only take half an hour.
On the topic of DV, those files are big but don't throw them away. They are like negatives.