Yeah gimp does ugly resizing. Python image lib would probably be better, or if you have access to photoshop that works very well of course (bicubic sharpen setting). Or email me the file if you like. :)

Other ideas- I'd make the top blue gradient extend the whole width of the page. If you're going to make your signup buttons with fancy css shadows etc, might as well do the same for your logo text rather than having it in an image. Any reason for the lack of spaces in 'Wireframing&Prototyping'? You've got 'learn more' text in two different formatting styles on the landing page. No need for external links to open in new tabs, your users will be savvy enough to use their back button. I'd consider burying the 'get it free' in the footer rather than by the buying info - perceived value and all that.