Requiremnts to attend/purchase - Check your States dept of Revenue and see the requiremnts for registering yourself as a small business. It costs about $100 total in IL (including a $60 newspaper ad). They give you a stat tax ID in IL, and that's all they wanted for the tech tour last year.
Reason to go - I went a few years and the event is worth a reasonable drive (for me it was only 40 minutes). They do give away t-shirts and they had a drawing from all the vendors. Drop a card in a bowl at each vendor table and they do drawings. Last year they also gave away a 64 MB jump drive with the presetnations and a mic/headset (I use it for BF2142 and it works fine). They do have quite a few vendors there (Ati - a given this year, Sapphire, Creative Labs, Tyan, SuperMicro, Enermax, MSI, Asus, etc) so you can get neat free stuff from them (key chains and the like) and also see some new technology.
Value of the bundle - Since CompUSA is clearancing software, Vista can be had at 40-50% off if you have one local. Taking that into consideration, i didn;t think it was worthwhile. Side Note - I will be visiting CU next week to check on price. I may buy a few and sell them here at the cost plus shipping (to give back to the community and all). I'm a bit worried noone will want them...
Sorry for the long post,
EH