ATI Mobility Radeon HD 6770 - 1GB vs 2GB ??

What's more important is the CPU that's in the laptop otherwise you have plenty of ram. Keep I mind that you wouldn't really be doing serious gaming on a laptop so in my opinion there's no need to go all out on a mobility GPU.

Why don't you spend a quarter of the cost of a laptop with those specs and setup a small footprint HTPC?

no, for video playback it wont even be using 16mb of video ram, so an extra 1000mb is totally useless. A faster multi core processor and more system ram is what you want.

The 6770 should have UVD for hardware video acceleration. You should not be experiencing hiccups and pauses, unless it is a network buffering problem. If you are watching videos on websites via Adobe Flash, make sure you have the latest version and that hardware acceleration turned on. If you are using some other offline player, find out if it supports hardware acceleration. If not, switch to a different player that does.

tofu2go: Can you suggest a player that uses hardware acceleration? I have a small assortment already - media player classic home cinema, VLC. I also have the latest k-lite codec pack installed. Any tweaks to do in there to assure flawless playback?

My PC is an "HP Pavilion dv7t-6100 CTO Quad Edition Entertainment Notebook PC" with a quad core processor and (now) a 2GB ATI 6770 video. I will run screen 1 at 1600x900 and screen 2 at 1920x1080 (if I can get away with it)

I ask all this because I am going to be running a playlist of 1080p and 720p videos at a convention in a week, and it all has to be perfect. I will edit the playlist on screen 1 as needed while the videos play fullscreen on screen 2. I am 99% comfortable with things as they are, but I saw that little pause recently...

ANOTHER ISSUE: I really want to do "theatre mode" to play fullscreen on screen 2, but can't figure it out with system 7. I can simply drag the player to screen 2, select fullscreen and play it, and keep the playlist window on screen 1 - but that's not as foolproof as running screen 2 in theatre mode. Any suggestions are appreciated!

Forgot to mention: above laptop has 8GB RAM. Thanks.

Use Splash player HD... It is free... It will use your GPU to play the videos... Just go to the settings and enable the GPU option...