Humming noise coming from microphone

I seem to be getting a constant low humming noise coming from my microphone. After some searching, i found that it could have something to do with my monitor, but that's about all i could really find out. I noticed that the sound gets quieter if i put my headset (with the mic on it) near the monitor, and louder if i hold it far away from the monitor.

I've tried fiddling with settings and plugging the mic in in the front and back sockets on my computer, but nothing's been able to stop this sound.

i don't think this problem has always been there though, i can remember a time i use the same hardware setup and the humming sound wasn't there, but i could be mistaken.

the monitor i have is: Iiyama Pro Lite E483S-S - LCD display - TFT - 19",
the headset im using just says Speedlink on it,
im using windows xp home SP3.

Does it still do it when you turn the monitor off?

DO you have another pc you can plug the mic into?

Try routing the mic cable farther away from the monitor if you can. It may be acting as an antenna and picking up RF from the monitors electronics/power supply. Also try plugging the monitor ac cable into another plug farther away from where it is now or at least routing that one differently as well.