By removing the relevant conduit you can opt to not sync the following elements using iSync:
1) Contacts with Address Book
2) Calendar and Tasks with iCal
If you sync Calendar then you must also sync Tasks and vice versa.
Similarly if you replace the relevant Palm conduits (that the iSync installer removes and stores in a separate folder) you can then sync either of the elements above with Palm Desktop.
What you can't do however is sync anything that's synced using iSync with Palm Desktop. So if you are using iSync to sync Calendar, and by necessity Tasks, then neither of these can be synced with Palm Desktop.
Substitute Date Book for Calendar, To Dos for Tasks, and Address Book for Contacts if you don't have one of the more recent Palms.
There is a description of how to mix and match conduits on Apple's web site. I can't remember where exactly, but a good bet would be to look at the iSync product page first.
Also make sure you're using the latest version of iSync (1.2 I think) - alone that might solve the missing info problems.
You're right, it's crap that the category information isn't synced. I'd suggest that you submit an "enhancement request" to Apple for this to be included in the next iSync release. As it looks like Palm may drop Apple support altogether, we soon may have no choice but to use iSync, so we might as well try to get it how we like it (unless of course the MarkSpace guys provide something as they say they might - though you'll have to pay for their syncing software).
