In reply to girlymonkey:
If it's the permethrin-based stuff you treat your clothes with, then yes, it's actually pretty good.
They can still get you if they go directly to exposed skin or an untreated garment, but it really does seem to kill/repel them from treated clothing - they sometimes crawl up a bit before falling off stunned (or dead?), but you'll even get less on your trousers in the first place.
It gradually wears off over a few washes, of course, so you'll have to re-treat again later. And I don't think it's very good for you - but then, neither is Lyme!