I have Ubuntu Dapper , maybe it is not the best, but in 100 % works with my laptop, and this is what I expect from the system. But, yes, I like Ubuntu.
BT can be used as a standalone operation system but what is missing is the repository of precompiled packets.
When installing the new program (like Nessus - next thread) you have to find and install the missing libraries one by one , while Ubuntu Synaptic
program lists and loads libraries automaticly and if the library needs another library to work it is loaded too.
So making the changes in 'full system' is easier than in BT (that will probably change with developing BT 3 ).
I use BT on USB , that saves laptop's CD , and you can easy add the changes to BT stick.
I suggest fast USB2.0 stick, otherwise it will boot very slowly.