The HP m9200t will run PS CS3 and LR just fine, assuming the CPU, RAM, and GPU have not been abused or overworked. If you are tech savvy, you could overclock the CPU and cool that puppy with coolant (the same type you use in car), and it will be almost as close as to the HP p6580t (not similar but close in terms of image processing), depending on how you do your image processing. The key is to take advantage of all cores and multi-threading.
If you do raw conversion and some basic editing during post processing of 500 images or less per session. The Q9300 is more than enough for your needs. The i7 would be overkill for an average user. Don't worry about the graphic card at this point. Even though a good graphic card does help a bit in photoshop, it still takes a lot of tweaking in the photoshop department to take advantage of all the graphic card has to offer (Adobe, are you listening?). Avoid gaming graphic card though, but look at good CAD graphic card for image processing.
For $250 (assuming everything is still in good sane working condition - no smoke, no funny smell, no click clack sound, the m9200t is a good deal!
Hope this help a little 



