For Hi continuous shooting, you need:
- a fast card (Class 10 or faster) like a Sandisc Extreme III,
- select a small file size (eg 6 Mp), and
- switch off any on-board PP.
The K-x has a very small buffer and you can only take 3-4 RAW files at a time before the camera slow down.
The K-7 has a larger buffer size and I have been able to get over 60 shots in Hi continuous shooting without any problem. I use a SD Sandisc Extreme III, I set 6 Mp JPEG file type, and I kill all on board PP incl. lens distortion correction, high ISO correction, etc ....
Hope that the comment will help.