Adrive offers 50gb of free storage online with the ability to share your files with other users (links only valid for 2 weeks with the free package). I'm not sure what upload/download speeds you'll get, but it should be fast enough. Alternatively, if you don't mind leaving your PC switched on, you could run your own FTP server using FileZilla and give your friends the logon details.
With 2 PCs side-by-side, use a gigabit wired lan for best speeds; both PCs will need a gigabit ethernet card (NIC) and you'll need a gigabit router to make the connection. However; even if you only have 100Mbit ethernet you should still get around 10 Megabytes/s sustained transfer rate. Alternatively, use a Firewire or eSata external hard-drive, or if you don't mind getting your hands dirty, get a cheap internal hard drive and swap it between the systems that you need to move the data to.
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