K7 is a good camera, however, the K5 is a even better camera. Technology has improved much on the K5. The improvements includes faster AF, better focusing at Night, Choosing Focus Priority or Release Priority, More controls over your camera Settings (For example, more USER Setting,5 instead of 1, Slow Shutter Speed NR could be off - Think this is one of the important thing for most users), better High ISO performance. It's more a All-rounder than K7. But at base ISO and if you are into Landscape only, K7 does it jobs perfectly.
If budget is a constraint, KR will be a good option for you have to have a feel of Pentax before you start investing too much in it.. It's even cheaper than the K7. ;p
This sums up the reason to get the K5 very well.