I have received my Sainsmart's Arduino MEGA 2560 (and touchscreen), it is, I think, a clone of the Arduino Mega 2560 rev. 2.
In the manual, they say to use the Arduino IDE v0023. What problems will I have if I use the most recent IDE ? Maybe I just have to modify a little the provided touchscreen libraries so that they compile fine (if there are errors...I haven't tried yet) ?
The touchscreen may use functions that have changed since V0023. I use a few versions of the IDE on my computers, so you can try a newer version without overwriting the previous versions.
One of the major changes was a header name change. The file WProgram.h is now Arduino.h. If you can live with small edits like that, I recommend at least trying v1.0.1.