I have a CD catalog that contains various o/s's, boot disks, Norton System Works, Benchmarking / diagnostic programs (SANDRA), etc.
I bring along a screwdriver with interchangeable heads, and a cool little computer repair kit with all kinds of little tools I've yet to ever use

.
I put all of this into my Laptop bag (with......my laptop

) . I also have a 40GB USB external drive that I tote around with me to do backups (not everyone has a burner - that would be too easy, huh?).
I would say that the tools that get used the most are a Win 98 boot disk, my screwdriver, and my external drive. I very rarely use any of the programs except for SANDRA as the copyright thingy

.
Hope that helps. 'Course there isn't any need to spend the kind of dough that I did to get started. I am just a tad bit obsessive (for lack of another word) and think that I'm only as good as the tools that I'm working with (again, most of them unused for the most part

).
Mike