Don't go for the SX1 just becaue of it's Full HD video capability! It has a major issue (as do most other CMOS sensor based cams) of giving a "jello effect" while panning horizontally. Google for sample videos and you'll know what that looks like. And Full HD video will really eat up your storage space much faster than 720p. And for all practical purposes, 720p video is really good enough.
If you don't mind the added bulk, go for a DSLR as suggested by other above. A Canon Ti two lens kit goes for approx $700-800 when the deals become available (as during the past week or two). You'll get waaaay better image quality.
Or if you're really willing to stretch the budget to $1k+, you can opt the Micro Four Thirds (DSLR-like, interchangeable lens, but much smaller) Lumix GF1 or GH1. There is no other digicam available right now that shoot better Full HD video than these two, especially when combined with the Lumix Vario HD 24-280mm (35mm equiv) lens, period! The GH1 with this lens goes for around $1400 and it's dropping in price. Apologies if this seems way out of your budget, but just giving you an idea of what's out there if video is also important to you and you don't want the hassle of carrying a camera AND camcorder wherever you go.