Oh and...you know something? Myself, my desktop was mostly for work, but I jumped it to gasmes and such. God, I regreted it...I was happy for gaming, but my computer was no more designed for work. Now, I'm reintergrating it to work days
I'll second jac for not building your own desktop. You never know, if it's a good tower for gaming, most likely people will break in and steal it. Dells, they'll run away from it...but I like them...quiet!
To answer your question, Bring the laptop. It is more easier to use and it can be placed more secure. BUT, if you want to bring the desktop, by all means. If you need to upgrade them a bit, o so. They look fairly decent to my criteria