Bluetooth for PowerPC G4

I am running a PowerPC G4 with Mac OS 10.5.8.
The computer does not have bluetooth so I will be adding a USB bluetooth adapter.
First, is there any advice about which make adapter or any special things I should look for in the adapter.
Also, is software needed to buy to use bluetooth to connect to my cell phone.
When I go to system preferences and sharing no bluetooth shows up under services.
Will it show up once a bluetooth adapter is plugged in?

hi,

i am a novice when it comes to mobile accessories. I am thinking about buying a new SE 750i, which comes with a bluetooth device. My question is that if i switch over to, say, Nokia N72, will the same bluetooth device work for that or will i need to purchase a new one for N72?

TIA.