I am just about to author my DVD, and have everything ready to go

Everything is looking spot on, the only task I have left to do before authoring, is the joining together of two of my DVD compliant files

I have acheived great results at all production stages thus far, and dont want to balls things up at this point

After browsing the tools database, I'm a little unsure which to go for, so, could someone point me in the right direction of the most reliable freeware joiner?

BTW, I am using GUI for DVD author, is it possible to simply place both files into this and let it join them somehow?

Cheers