Now this *is* dead simple - windows 95/et.al has automatically named your drive disk2_vol1.
It's still your D: drive, but if you really really need to change the name, fire up windows explorer, right click on the D: drive and select 'properties'.
That window will show you a box titled 'label'. Just type what you want to appear next to D: in it.
You don't need to do any of the above - your drive will function normally regardless of what name you give it (a 'volume name' to quote the industry I have happily left behind !).
Cheers