I had a similar problem. I'm setup to dual boot XP and Win 7 with additional drives for storage. Like you nothing was showing up in Win 7 recycle bin. It's odd but I noticed the settings for Recycle Bin in Win 7 were not the same as the settings in XP. I changed the settings in both OS's to match each others OS and the custom size for each storage drive was set the same. All drives had different custom sizes but I made sure they matched in XP and Win 7. Example would be
XP C: 4 gigs
Win 7 E: 2 gigs
Storage F: Don't move files to recycle bin
Storage H: 11 gigs
After the sizes above were the same for recycle bin in Win 7 as they were in XP, the files started showing up. Weird I know but it worked for me. May not apply to you but sharing info just in case