I have read 3dfx's press releases stating their Voodoo 3, Voodoo 4 and Voodoo 5 have hardware assist (planar to packed-pixel conversion) but I have yet found a software dvd player that utilises the Voodoo's hardware acceleration features.

Was this just a gimmick by 3dfx or does their cards have hardware dvd acceleration but requires a certain version of software dvd player?

I witnessed the acceleration myself, but only in old (of these days) DVD Players.

I imagine modern players possess no 3dfx Driver support anymore (function set is not recognized), thus the available hardware acceleration features remain unused in current Players.

To see if they are properly implemented in the used Driver, typical GPU Analysis programs should display available functions.

It was a very useful function, I remember it made all the difference between extremely high CPU usage (NVidia Cards of these days) and quite low CPU usage (3dfx).
Only ATI was in front, AFAIK they were the first to implement very far reaching decoding support in hardware for their time.
The 3dfx Hardware allowed a mere AMD K6 233MHz to fluently decode what otherwise required a more speedy (and more expensive) Pentium II.

Several of the retail 3dfx cards that I purchased here in the U.S. included mail-in offers for InterVideo WinDVD 2000 where you only had to pay for the shipping (about $4.00US).  So that version is probably one of those that FalconFly is referring to.

I checked the Readme file, and it lists (only) the Voodoo Banshee specifically.

Can you still obtain older versions of DVD applications like WinDVD 2000?

wrote on 21.12.07 at 08:00:27:

Can you still obtain older versions of DVD applications like WinDVD 2000?

I have WinDVD 3 and 4 I think, use version 4 on a regular basis. One version came with a Voodoo 4 era board so it might have the support.

I would suggest getting a demo or trial version before spending real money on one.  Tucows has a demo for WinDVD 4 for example:

http://www.tucows.com/preview/228053

That should be enough for a hands-on test of the card you have in mind.

I have an OEM version of WinDVD4, do you think there would be any issue?

I am looking at a copy of the InterVideo WinDVD 2000 that I mentioned above, and it is marked "Not for Retail Distribution," so it is apparently an OEM copy as well.  It is P/N 270-0046-001, Version 2.1.  There is nothing on it to indicate that it is for 3dfx cards only or that it is anything but a generic OEM disk.

I was looking through my old CD collection for older versions of PowerDVD and WinDVD.

I found I had an OEM CD of PowerDVD 3.0

but I'd really like to try PowerDVD 2.55 and WinDVD 2000. Does anybody have the trial versions of this for me to try?

Are you still looking for these trial versions?  I came across what appears to be a trial version of Cyberlink PowerDVD 2.5 this morning.  The filename is powerdvdtrial25.exe and the file size is 2.81 MB.  PM me an address if you would like me to email a copy.