Re-downloading ALL apps?

Hey guys,

In preparation for the new iPhone software upgrade + new iTunes, I want to do a little house cleaning. iTunes is reporting 75 apps in my library, but there are 171 files in my Mobile Applications folder. Most of them are just duplicates (new versions, etc) which I can safely delete. I'd like to just delete them ALL, but I'm wondering - how can I get them back? Would I have to re-download them one by one? And if so, is there some way I can get a list of all the apps I've purchased, without having to dig through dozens of iTMS receipts?

Wirelessly posted (iPhone 3G (16GB, 2.0.2 JB'd): Mozilla/5.0 (iPhone; U; CPU iPhone OS 2_0_2 like Mac OS X; en-us) AppleWebKit/525.18.1 (KHTML, like Gecko) Version/3.1.1 Mobile/5C1 Safari/525.20)

Thanks for the replies, guys. It sounds like it would be a major PITA to delete everything and download them all over again, so maybe I'll just keep them around. What's 500MB of wasted space, anyway. /sarcasm

Although one good thing has come of this - I actually went through my 34 receipts for app store stuff and got everything onto a spreadsheet - turns out there's about ten apps I downloaded back in July that I had completely forgot about. Now that the iPhone will actually be able to handle them (with the 2.1 software) and install them in less than four hours, I think I'll download them again. So, some good came of this anyway.