i found a way to permanently add the subs I have to the avi, bu running it through VirtualDUB. You just have to make sure, you select th eVobsub filters.
To do so, clcik video->filters and push the Add buttin. In the popup select the filters you want VirtualDub to use. I want subs added, so i select the VobSub filter near the bottom of the list.
Now run the avi through Virutaldub and let it make a new avi. This will have the subs hardburned.
Needless to say, that it is out of bounds for this thread to cover all the other preferences in VirtualDUb you have to set, in order to not screw up an already perfectly riped avi .-)
I found another way to convert my subs, which are from a chinese sub-program into another format, by using a combination of submax and vobsub and then import the subtitles into DVDmaestro. I tried this method and it worked flawleesly too.
Hopes this helps somebody