Can this damage my laptop's graphics card? Overheat?
I'm running a ATI Radeon 3650HD 512mb on it.
Nope that is why they have those ports.
go for it. i had mine up on a 60" plasma, and it looked gorgeous.
EDIT: if your lappy gets very hot under a heavy load, i highly recommend propping it up for maximum ventelation. also, consider downloading a core temp. monitoring software. rightmark CPU clock utility is great; it shows your temp in the notification area next to the clock. if it goes over 70C, shut it down immediately.