Condensor microphones are fairly standard recording gear, and have dropped a lot in price in recent years (they now start at about £30 - 5 years ago it was £100). They do require phantom power, and the usual way to attach one to a computer is via an
interface that will provide 2 or more inputs and then link to the computer via USB (about £100). However you can now get
condensors with a USB link that will draw power from the computer and cut out the need for the interface - however with an ordinary soundcard you may find this results in latency issues (ie if you play along to the sound coming out of the speakers it won't match up - there's a time lag). All of that applies if the mic is for home recording.
If the mic is for live use then dynamic microphones are the way to go -
the shure SM58 is the industry standard on the basis that you can hammer nails in with it, use it to beat a member of another band to a bloody pulp, throw it out of a hotel room window, and still use it to sing into afterwards.
These AKGs do the same job, cost less and sound better (but might break if you hit a roadie over the head with it). Finally if you wanted something more basic I have one of
these Behringers which I used as my only mic live and recording for a couple of months, and still use as a harmonica mic - it has a great sound for its tiny price. And
Shure PG48s are also very good for budget mics.
I hope some of this made some sense to you, please feel free to point out anything I need to translate into english
Wormella has just told me we need a 'I bet you wished you never asked' smilie.
edited for a rogue apostrophe