Can I do 'batch' Track number?

Hi. I've been using this tool for a few hours now and it is amazing. I've worked out a few things but not, so far, this:

I have a folder of songs all taken from various sources. I have them in order by having each file name start with a number e.g. "001 Waterloo". The Track tags are either blank or have the Track of the original source. Is there a way of allocating new Track tags - starting 001 and increasing +1 each time - without having to edit each file individually?

My thanks for any advice offered.

EDIT: IGNORE ME - I've just found the autonumber wizard. Great stuff...