thanks all for the tips, and will do Tim if i get outta control. just freaking a bit as this is my 3rd 20D (can u believe it) in less than a year, 1st one got returned in 15 minutes after big bit of white crusty stuff stuck to mirror when i went to attach lens, 2nd was returned as was full of dust when i purchased it (i believe) and got sensor clean from wps and it came back to me with more crap inside it than when it went in, had to fight for a new one as they didnt want to do it, kinda sucks this whole sensor/dust thing as i dont even take my lens off having only one,
but on a cheerier note, thanks again for all wisdom and tips, i'll have many more questions about various things to come