.mac iDisk/Mail Disk Space Allocation

Apple's upgrade of .mac to 1GB of storage space was most welcome, however something is niggling me. I don't use much mail storage space, but have an almost full iDisk. Is there any way to adjust how much space goes to each? I could upgrade my iDisk to 2GB, but then I'd be wasting even more space on mail.

I've looked on the .mac preference panel and on the mac.com web site for a setting, to no avail.

Great, thanks. Think they should have mentioned that on the iDisk page, I didn't think to look there.