Another question from my side: "What is the minimum resolution my game should support?"

I grew up with a very shoddy computer and was THRILLED when Half-Life let me play on 320x240. Trying the game on 640x480 was absolutely unplayable. As a result of this experience, growing up, I've always tried to accommodate the lower thresholds of computer resolutions, whether it be in programming or HTML, etc.

HOWEVER!- Do people really use such low resolutions anymore? Up till now I've tried to always make sure something could be viewed on at least 800x600. Would it be very bad to step this up to 1024x768? My conscience seems to say "yes", but I'm not sure.

I'm working on a project that involves a 2D tile-based world, and if a larger resolution means I get to fit more tiles into one screen, shouldn't I go for the larger resolution? Creating a scrolling map / split screen is out of the question. Thus, resolution pretty much determines map size.

I've thought about maybe making separate 800x600 maps and 1024x768 maps and then accommodating both, but it doesn't seem very elegant.

Thoughts / ideas?