creating rounded graphics and round corners?

just use css3 to do it. at this point, if you're using a browser that won't support it in some way you're either:

• using it voluntarily, therefore odds of you noticing the corners are sharp or rounded (and then caring) are next to nothing and not worth the effort anymore.
• being forced to use it and rounded v sharp corners are the least of your worries.

unless the design calls for photographic details the arguments to hack together graphics vs just coding something that degrades nicely are very limited.