IMO, the two are about equal in photo quality. The SX230 offers 1080 vs. the SX130's 720...whether there is an actual improvement I do not know (numbers are not as important as actual performance). They both offer P/A/S/M controls. So it mostly comes down to features. The SX230 has quite a few more, some which I think would be useful...but it cost quite a bit more.
What camera should I buy considering the following aspects:

Chowhound
Comic Vine
GameFAQs
GameSpot
Giant Bomb
TechRepublic