So I just bought a new computer and I was wondering if there was any way I could transfer my game files from my old computer to my new one, because I really don't want to have to download all my games off steam again (which would take hours upon hours), and then have to re-download all my mods for those games again- the save files don't really matter to me, just the games themselves. So far I've downloaded all my steam data onto an external hard drive, and I was wondering if this is all in vain, do I just have to redownload all my games from steam.

back up steamapps folder

when you reinstall steam if you copy in the steamapps folder it will know what to do with it when you launch steam for the first time with it

Thanks for anyone giving assistance, but I totally figured it out (mostly by accident, less skill).

I had to do this this past week(built new pc), although i had to redownload some data for some games because it wouldn't validate some files after i tossed them back into the steamapps/common folder but otherwise most of them worked with no problems.

Earlier this summer I built a new PC and had to do this.  I recall backing them up, but only expecting the save data to come over.  I was happily surprised to see most games didn't need to be re downloaded.