Scanner

I am new here and not sure where I should post this , so please be forgiving if I am in the wrong spot.
I have a chance at a nikon CoolScan IV

The asking price is $300 , I am sure I could get him down to about $250. I dont know what the true value of this scanner is but $300 is about my spending limit.

I looked it up on the internet and it seems to only be about 2900 dpi. Nikon's current model scanners are at 4000 dpi.

So how much difference is that ?
Are their any current drivers that will allow it to work with windows vista ?

How does this compare with some of the Epson scanners that are at 3200 x 9600 dpi ?

I see some epson that are 3200 x 9600 dpi ranging in price from $90 to $700
What is the difference?
How do you choose a great scanner?
I have no clue about scanners so any other advice or recommendations are welcome
Tom

I think you'll have better luck over here... http://www.hybridphoto.com

Thank you Travis. I have posted there too.

Scanner questions are generally off topic at APUG, unless they are specifically about posting images in the APUG gallery. APUG's sister site, hybridphoto.com, is the place.