Thank you very much, Pyro.
No worries. 
I'm a newcomer to arduino and to programming and I never heard of near/far Progmem before.
It is quite rare for people to run into the far range of memory ( while using Arduino ), but there is a load of information out there about it.
If you are using loads of images/sprites it may be better to use an SD to store large sets of images. It is far slower than PROGMEM, but writing them as one large file might speed things up when it comes around to reading the data back.
Not to worry though, at 100k you still have a fair bit of PROGMEM room on a Mega 2560