How to set up system to play DVDs?

I have just installed a Samsung CD-RW/DVD drive that I picked up second
hand and I can't get it to play DVDs.

As I've never had a DVD drive on my PC before, I thought I'd better check
what I need, in terms of both hardware and software, and anything else
I'm missing in terms of setting it up.

1. First of all, do I need any additional hardware, eg some sort of PCI
card decoder that works with the DVD drive?

2. Secondly, in terms of a software DVD player, according to the
Microsoft webite there is a DVD player included with Win98, but I can't
see any way to install it from my Win 98 disc. The MS website seems to
suggest it will only work with certain DVD drives anyway?

In any case, I downloaded a freebie player (Cliprex DS DVD Player) but
still no luck - after launching the software and pressing play, I just
get an error message sayinmg there isn't a DVD in the drive (I tried
several DVDs with the same result).

What about Direct X? Should 8.1 be ok or do I have to upgrade?

So I could use some pointers here as to what I need to do to get my DVD
drive playing DVDs, thanks.


Jon

PS

The drive is installed as secondary master, is listed correctly under
Windows device manager and plays back CDs just fine.

[Windows 98SE with Direct X v8.1, Athlon 1.8G, 512Mb Ram, Terratec DMX6
fire soundcard, motherboard onboard video (Via)]