That looks like the PB 810 motherboard:
http://uktsupport.co.uk/pb/mb/pbmb1.htm
i430VX chipset, 168p DIMM only, some or no cache. That last point is critical. If it has 256kB or 512kB L2 cache, it's potentially a perfectly decent i430VX system, which is period-correct for Windows 95 and will run late DOS things very well. No cache and it's hamstrung and will perform terribly.
As for sound, it looks like the board has a CS4237 onboard. That is - in general - quite a bit better than that SB16 Vibra card; it has bug-free MIDI and CSFM is generally considered quite a bit better than CQM. The only benefit of the CT4170 is 16b SB16 audio, but CS4237 give WSS which is better if slightly less widely supported.
96MB RAM is a bad idea. i430VX can cache 64MB max. If you're talking games, nothing was released that would run acceptably on a P1/i430VX that needs >64MB, so there's no benefit to it. Keep it at max 64MB and even then keep a nice big disk cache.
As for a GPU - the GeForce 256 was the first GPU and even if there was a PCI version of it, it would be complete overkill on this system. For DOS, the onboard S3 Trio is already pretty much ideal. For Windows, it's fine for 2D as well, and for 3D a Voodoo would be a possible upgrade, although there again most Voodoo games would want a beefier CPU so there are not many that will benefit from a 3D accelerator on this system. If your pockets are bottomless or you can get one, but don't expect miracles. Dark Forces 2 was released a year after this system, Half Life another year after that. By that time a >300MHz P2 with AGP graphics was the default and even they would have run it slowly, certainly by today's standards. I'd stick with DOS and 2D Windows 95 stuff on this system. If it has cache. If not, DOS and Win3.x at best.
