Ive got Rocksmith on my laptop which I run through steam can I log into the PC downstairs and use it on that aswell?

Yes I run it on my Desktop and Laptop.

 

All scores/progress information is synced with your Ubisoft account and Steam, so everything will show up the same. Only thing you would need to do is to make sure you keep the dlc folder files the same. I download all new/updated customs on my laptop then when I want to play on my Desktop I delete the old dlc folder on there and copy over my laptop one to stay current.

I use Dropbox and a small third-party app to keep my dlc folders synced.  You can't natively sync folders outside of Dropbox, but the app allows you to create symbolic links to the dlc folder, which then uploads the files to Dropbox.  Using the same app on my desktop, I can then sync them there.

 

That way everything is synced automatically and I don't have to worry about deleting, or waiting to copy every time I switch computers.  I just sit down and play as if I never switched.

cheers for the reply will give it a shot