howdy, welcome to the forums
first, what OS are you running on your new system? Is it Vista or XP?
second, have you tried doing something like this yet?
1. "save" a torrent in Bit Che to your hard drive
2. double click the .torrent you saved in Windows Explorer
3. it should ask you how you want to open the file.. so just find 'Opera' and click OK
4. from now on, 'Opera' should be properly associated with .torrents and Bit Che will have no problems sending them to the client..
if that doesnt work, let me know and I can take a closer look at Opera itself.
thanks,
chip