Hi jwforeman,
I didn't do a PPL before hitting the ATPL, and don't regret it in the least - but I'd advise anyone starting out to do it for several reasons:
You find out whether or not you have an aptitude for it or whether it makes you sick!
It'll give you a head start into professional training, and it allows you some leeway as to whether you want to do modular or integrated training (Perhaps others who know more can correct me, but I think sponsorship schemes are few and far between - although take a look at Flybe, I know they do a part-sponsored one)
And perhaps most importantly, it shows long-term interest in aviation when you do get to the job/sponsorship interview stage! Or you could simply plead poverty like me and tell them your ASBO kicked in straight after classes.