So I finally took the plunge and upgraded to Leopard, it went smooth as silk, until I got home and wanted to connect to our wireless network and it failed with "Connection Timed Out." Sigh...
I have a Westell VersaLink 327W DSL "modem" here at the house and that was the cause of the problem, I needed a firmware upgrade.
Following post #12 on this Mac Rumors forum post fixed my problem.
Good luck to you!
Here's a link to the VersaLink firmware upgrade.