Miken12
"...So I just installed a voodoo3 2000 PCI video card in my computer yesterday...does this mean I have to install a fan to it too??"
If you intend to oc it do so. If you want piece of mind, you can do it, too

. In non-oc'd situations the stock heatsink is decent if not glamourous.
If you want to go all out (in either oc'd or non-oc'd instances) and by voiding your warranty

), you can take off the retail heatsink and slap on a Lasagna V3 Stealth cooler from
http://www.tennmax.com. Great fans, but you get what you pay for. Had my V3 2000 AGP oc'd to 166 and 183 using the Lasagna V3 Stealth.
Deeko
"...the fan on my Viper 770u died, so I put a slot fan directly below....will this be just as good?"
Is the board still under warranty? If so, RMA it and grab another one. If not I would replace the HS/fan combo with an after-market one --OR-- this'll be a good opportunity and the perfect excuse to buy a new vid card.