MAN you guys are going about this in the wrong way. Look, you need to format your HD in your PS2 do not, i repeat do not format it using winhiip or you will be in for a serious surprise.
AFTER you format the HD in the PS2 It WILL NOT be seen as a device under "my computer" because it is now a PS2 hard drive.
The reason why you are not seeing the drive under winhiip when you connect to the computer is because you have to switch the little plastic cover at the back where it has the slot of four pins so that your drive reads as a SLAVE when you put it back to your cpu because obviously, your main hard drive will be (or should be) your MASTER. Do that, and you should see it in winhiip. I hope you're turning your Pc OFF before switching drives or youll wreck your hardware.Don't wreck your hardware. If it works and it allows you transfer your games from the main hard drive to the ps2, remember to SWITCH IT BACK to master before you put it in the pS2 or it wont show up. If you do all this and it doesnt worked you're screwed!