I use RTcomm on my tablets for Google talk, MSN, and facebook, not that I'm a heavy chat user myself either.

RTcomm works for me as it is built in to the system, and all the notifications etc work out of the box, and intergrate nicely with the whole ecosystem on the tablet. RTcomm allows you to set your visibility using the presence applet on the panel, which is quite neat

I tried pidgin a long time ago, and I felt like it was just an app which sat on top of the OS, and for me at least, if it was not running, I was not visible.

I would suggest giving RTcomm a spin first.