Sound through graphics card?

The ATI 5000 (and 4000/3000) series of cards comes with a sound chip built in, so once the sound driver is installed, you cen get up to 7.1 sound using a DVI->HDMI connection.

That being said, the Samsung Syncmaster HD series (I have the T240, BTW) have optical outputs which can only carry 2.0 (maybe 2.1...) audio. I tried streaming 5.1 Dolby/DTS signals and got nothing but garbage...Now, if your speakers connect via optical digital, you can pass that signal through, but if you connect via analog, you're best option is to still plug into you're computers onboard (or dedicated) soundcard.

BTW, I believe the chip on the 5000 series is a Realtek chip, so I can't imagine quality is any better then standard onboard anyways...

Probably not; most moniters have only output ports...

In theory, assuming you're moniter had analog input ports, you could fake 4.1 (no center channel) by plugging your speakers into the analog output for front L/R speakers (Green), and using a male-male 3.5m cable to the outputs for the side speakers to the moniter. I did a simmilar setup a few years back for a cheap 6.0 setup (fronts, sides, and rears) using 3 pairs of cheap desktop speakers (a total wiring mess though).

What I would do, since you do have input ports, is this:

As the input ports are RCA (two inputs for stereo sound), get a cheap 3.5mm -> RCA converter cable (male on both ends). Then do the following (from you're PC):

Green 3.5mm output -> RCA converter -> Inputs on moniter (L/R speakers)
Red (or is it black?) 3.5mm output -> Speakers (Rear L/R speakers)

This would give you a quadriphonic (4 speaker) setup. Alternativly, you could select 5.1, and you'd simply have no input for the center channel.