CMOS battery location and replacement

I have found recently that my Inspiron 1150 is losing time on the clock. I have reset it numerous times and it will continue to lose time. I am thinking that maybe the cmos battery needs to be replaced.  I had to replace the motherboard about 6 months ago with a used replacement board that I found online. I was looking at the old board and I didnt see the normal small round watch type battery that is in most desktops. I did see a small silver one with a purple edge that is soldered to the motherboard. I was wondering if this was in fact the cmos battery? And if it is has anyone ever replaced one? I have never soldered on a motherboard before and I am alittle worried about messing it up. Any help would be greatly appreciated!