The highest resolution supported by the PT-EZ770 is 1920 x 1200 (WUXGA). That's over seven times the resolution of a 640 x 480 (VGA) projector, which is the most common resolution supported by 5000:1 contrast ratio projectors that came out around the same time as the PT-EZ770.
A 1920 x 1200 (WUXGA) graphics resolution is in fact the best supported resolution across all comparable spec multimedia projectors that have been on the market for a similar time to the PT-EZ770.
A 640 x 480 (VGA) graphics resolution is the worst supported resolution across similar types of projector.
Projectors with a higher resolution that might also be worth considering include the Optoma EH7700 (1024 x 768 (XGA and cheaper)|1280 x 1024 (SXGA and cheaper)|1280 x 720 (HD 720 and cheaper)|1280 x 768 (WXGA and cheaper)|1280 x 800 (WXGA and cheaper)|1360 x 768 (WXGA and cheaper)|1400 x 1050 (SXGA+ and cheaper)|1600 x 1200 (UXGA and cheaper)|1920 x 1200 (WUXGA and cheaper)|640 x 480 (VGA and cheaper)|800 x 600 (SVGA and cheaper) and cheaper), or the NEC PA522 (2048 x 1080|4096 x 2160|1920 x 1200 (WUXGA and cheaper)|2560 x 1600 (WQXGA and cheaper)|640 x 480 (VGA and cheaper) and cheaper).