The amount of RAM you have doesn't make a diff re the resolution you can power m8.
You want to look for a screen with a res of 1900 x 1200 or less.
Whats all the "only does 1900 x 1200"????? Thats a superb res mate.
As for an HD TV what are you looking at using your computer for? Web design? Logo Design? Photoshop or any other type of pro use where colour matching is essential? If so get TV out of your head and get a monitor. If your just viewing the web and watching DVD IE none pro use an HDTV would be fine.
Hope this helps. If it does please DONT rate me up. I hate the idea of this rep thing. Instead I am collecting warnings for swearing like John Sparton of Demolition man