Switching from your S3 IS to the SX130 IS would be a sideways move. The only thing you would gain is a smaller camera size, and bigger images, 6 mp vs. 12 mp. Image size won't make a difference unless you habitually print or view at the maximum.
UV filters are pointless on digital cameras. Digital imaging sensors do not respond to UV light.
I am considering switching to SX130 IS, but am concerned that that camera won't allow for attachments such as uv filters. Would this be a significant upgrade for me that is worthwhile? Or is the SX30 IS better, but of course it is in an entirely different price range. Not sure I can spend that money.