Why is my PS3 so slow?

when i download demos or updates on the ps3 it takes 5+ hours to do so! My connection speed is udder crap for my ps3 (download-800kb/s, Upload-100kb/s) so i know that has something to do with it but i think it has to do with the ps3 itself, its one of the older 37gb versions. My xbox360 which sits right beside my ps3 only takes like 20-30 minutes to download demos and only like 5 minutes for updates. My sisters boyfriend brought his ps3 over a few days ago and it sat right below mine and he downloaded an update in like 10 minutes and then downloaded and installed a game in about half an hour which i don't get how! Could it just be my ps3 being very old and could buying a new 250gig one solve the problem?