I get jpeg images in various sizes that all need changing to 580x300. Normally I do this is Fireworks. I then select jpeg and Export the file so I get a compressed image in jpeg format. Next, I upload to WordPress.

However, I now want to outsource this process. Are there any good online tools (ideally) or free applications that will allow the automation of this process, so they can be done with minimal effort?

When you upload to WordPress, it says crunching. Does that mean I can skip the step exporting jpeg so it reduces the file size?