If I want to use my microphone through a stereo system, shall i get an XLR to mono adapter or XLR to stereo?

Are you meaning to convert the XLR line to a standard "guitar" 1/4" plug?

If so you will need a loZ to hiZ transformer or a DI box.
get an XLR to TRS (stereo) to keep the line balanced. you wont need a DI that way.

Dr. Z Stangray
G&L ASAT Classic (Ron Kirn Custom T-Style coming soon! ronkirn.com)
Keeley 4 Knob Compressor
Taylor 314ce
ah okay, is it not possible to use an adaptor? I was hoping to just buy one mic lead so I could use that when going into a mixer etc, but i guess i will need to by 2 types of cables now?