Hey, congratulations on the acquisition of the 300D! That is the original EOS Digital Rebel, right? That one has a bigger, more comfortable grip (to me, at least) than the newer ones, and I believe it still also had the separate status LCD, which is a good thing, IMO. Also, your 75-300 just became a 120-480, which will help a lot in getting up close to the little buggers. You will still probably need to set an ISO of at least 400 in most cases for the shutter speed to be fast enough for the little buggers without blur.
Are you saving the K2 for a backup, or are you going to try to sell it?