I've just installed a 300GB HD. I was having trouble getting my wireless connection back up, so i was switching between the new drive and the old windows drive.

When i was plugging the old drive back in i put my hand on the front of the comp to steady it when i connected the cable, i must have touched the start button cos as soon as i plugged the power lead into the drive it started up.

Now all i get on that drive is the NVRAM message, i've left it about 5 mins but it's still hanging.
Have i fucked the drive or will it eventually boot if i leave it?

Sounds like its fucked. NVRAM is your hdd so the message is important, what is the message?

checking NVRAM...update OK

and then it just hangs.

I've googled it and people mention irq conflicts but i didn't think any of that was relevant to me.

I changed it to slave with the new one as the boot, same message.
Other people have said it hangs from 10 secs to a minute, maybe i should leave it for half an hour or something, see what happens.

I may post this at FH as well, see what i get.

I don't exactly get the problem. What drives did you change? Are they external? What start button did you press? What cables did you actually plug in?

There internal drives.

I've just installed windows on a new drive, i kept disconnecting that and plugging in the 'old' boot drive so i could access the internet as i was having trouble setting up the connection on the new drive.

When i'd done it i wanted to connect the old drive as a slave to copy files from it. When i was plugging in the ide cable into the back i held the front of the comp so i didn't push it across the floor and accidentely pressed the on button. When i plugged the power cable into the old drive it booted up, and i think i've fucked it.

OK now I think I understand it.
When you pushed the "on" button the IDE cable was already plugged in and the power cable wasn't. But you plugged the power cable in after that while the computer was already running. So the hdd might got damaged while you plugged in the power cable. Correct?

Try to do it again, maybe it helps.

Pin or cable damage from all the plugging unplugging? Just a thought...

I can't see any damage on the pins. I left it for 20 mins earlier, still no good.

Damn, there was a LOT of stuff on that drive i wanted.

Damn john, thats bad news..
Rule of thumb: If ever entering the PC to clean it or do any maintenance, always switch off the powersupply first.

Long shot.... have you tried a cold boot?

Replace the ribbon if you have a spare too, probably wont help but anything is worth a try at this stage.
Also try a different IDE slot

yeah, not much help but always take out the kettle plug, not only do you risk a short, you can turn it on by surging the power which can happen by plugging and unplugging components.

This particular problem doesn't happen with SATA mind.