Can this....?

[endrien]

Well Im going to be making a custom game system type thing from a micro atx computer so Im wondering, What emulators can I run with it? Im assuming I can atleast get up to N64.
Specs
P3 computer 800MHz (I might be 950), Geforce 256, Happague WinTV NTSC TV tuner, 8GB HDD, 512MB RAM
Thanks
~Alex

[FatTrucker]

Most modern iterations of emulators use fairly modern features like DX8, various plugin based emu's like PJ64 will also require something a little more up to date. So on that rig you will need to find older versions of most emulators that are more compatible with the hardware.
Version of Mame from 0.107 upward won't work properly on it, and you'll have the same problems with Playstation, N64, and a number of others.
You might be OK with things like Gens, and Snes9x but again, I would expect to experience random errors and/or slowdown with any up to date versions of the emulators because that hardware is just so far out of date now.

If you're looking at using it as a TV based all in one emulator system I think overall you'll be pretty disappointed.

My current dedicated emulation rig that I use with the TV is a 2.1Ghz Athlon 1Gb of Ram and a Geforce7900GS and its just about ok for 99% of stuff, but even then it will experience occasional performance probs. For modern emulators though, I would say this spec is a reasonable minimum for across the board compatibility nowadays.

2Ghz Processor
1Gb Ram
Windows XP
Direct X 9 compatible Videocard.

[endrien]

Really? Why would It be bad for a tv based emulator system? I mean it clears the req specs for project 64?
what about this?
http://forums.benheck.com/viewtopic.php?f=20&t=28689

[FatTrucker]

You asked for people's opinions and in my opinion running on ancient hardware is a PITA and a waste of time.
Whatever minimum specs are posted (these don't always reflect playable speeds BTW just physically getting things working), you will have issues with a lot of emulators on that hardware.
If you want a multi-emulator system that will run current versions of most emulators then you'll need something a bit more recent. That doesn't mean you need to go out and blow a grand on a top spec multi-cored beast.

Versions of mame past 0.107 won't run with a playable framerate on at least 75% of the games on that hardware, the latest version of Model 2 won't work at all on that hardware, using up to date plug-ins with PJ64 will cause issue on that hardware, same with ePSXe.

Its entirely up to you. I've visited loads of places where people have reported being able to do magical things with their hardware or where people get results that defy the norm, but I also post on a lot of support forums like these where people are having problems because they are using similarly specced hardware that's stopping them from getting the results they want.

If you don't want to have lots of niggly issues, incompatability problems, slow down and the ability to update your emulators as newer versions are released then you will need to use better hardware. The choice is up to you, but you asked for people's opinions and that happens to be mine based on the 7 or so years of experience I've had with different PC's and using different emulators.

As I said previously you can get usable results on that rig but you'll need to use older versions of lots of the emulators to get satisfactory results which if you read through the reply's in the thread you linked to is exactly what they said too. The specs they've posted for PJ64 are way, way out of date too and I think relate to one of the earlier versions of the emulator.