Which controls are you trying to use in MOSS07? Right now the RadEditor and RadMenu are the easiest to use in MOSS, but in a few short weeks we will release wrappers for all of the RadControls for ASP.NET AJAX so you can easily use them all in SharePoint.
If you are trying to use RadEditor, let me know and I'll be happy to point you to the wrapper we've already created for that control.
I'm happy to see you've found your solution. If you're only after those two controls, you have some extra help. Telerik has previously published a whitepaper showing you how to integrate RadMenu in to SharePoint and our RadEditor already has a pre-built MOSS wrapper. If you get stuck next week, let me know so I can point you to those resources.
Otherwise, check back in a few weeks and we should have MOSS wrappers for all of the ASP.NET AJAX controls.