I shoot both Pentax (DS, K10D) and Olympus ( OM, E300, E330). Olympus to use the older (very expensive OM) lenses already owned. Of the two systems greatly prefer Pentax. All the things we take for granted aren't so easy on Olympus. No infinity mark on lenses, no cable release on many bodies (E300 only with optional grip), etc.
Putting Pentax lenses on Olympus.
The lovely 43 won't be the fov you love because Olympus has a 2x crop factor. You also have to buy the Pentax adapter. Last one I saw was over $150 from Camera Quest! You will be using the lenses in stop down metering mode. Can understand doing this with old lenses where theres no choice but why would one want to do this with modern lenses like a 43? Live view is useful for focusing at 7 or 10X. It is also very slow and clunky to use. Remember the viewfinder is about half the size of a K10D so you lose focusing ability there - lots of it. Olympus also has a different proportion to its images than the Pentax (or any other slr brand). Even if you like it it will change how you compose. You also give up AF! If someone is having trouble focusing doubt its a good idea to give up AF to get liveview (to help focusing) on AF lenses

.
Would buy the K100D/s or the new K200D if I wanted a smaller camera body. Consider the fact that I own 10-17, 16-45, 18-55, 31, 77, DFA 100 macro, A*200 macro, and A400 and have never bough an adapter to use them on the two Olympus bodies.
E510 is a nice body. Will probably add one to my OM setup to get IS. Glad they did that.
thanks
barondla