ok So here is the list of what we're working with here:
S-Video-2600
-SMS
-Genesis
-NES
-SNES
-3DO
-N64
-Saturn USA
-Saturn JPN
ComponentWii
PS2
Xbox
VGADreamcast
DVIHTPC
PS3
360
Unless you want to front the money on a stand alone scaler for your S-Video devices I think the only thing were going to do here is find a solution to ensure that everything is organized and no signal gets fed through more than 1 switch.
For the 2600 if you're not adverse to soldering you can try any of these S-Video mods here:
http://www.cheeptech.../2600mods.shtmlOn a budget I'd go with Ben Heck's mod, or if you can front the cache the best solution goes for ~$150ish installed. That all depends on how much you play your 2600. If you're against cracking the case open then you can go to radio shack and buy an "RF Modulator" to convert the coax to S-Video... it wont be sold as a converter or adapter they're called RF modulators and they're sold as such... I saw 5 different models for sale when I was in radio shack last week.
Now you never told me if the DVI ports on your TV were DVI-I or DVI-D and that has some bearing on the next part....
For your DVI/HDMI devices I recommend picking up one of these switches:
http://www.monoprice...amp;cp_id=10110If your TV has DVI-I then you could pickup a cheap VGA/DVI adapter for the Dreamcast and run it through the same switch Otherwise I'd suggest plugging the Dreamcast directly into the TV's VGA port.
I'd also recommend getting a Psyclone PSC01 switch.
it's a 4 port switch and can handle component, composite, svideo, stereo rca, optical and even network (though I find network rather useless).
You can hook up your Wii, PS2 and Xbox here... also since it's got both Component AND S-Video Connections you can double up on each of the ports meaning that you could put 4 of your S-Video devices on this switch as well.
Assuming you have at least 5 S-Video inputs on your new Receiver you can use it for the remaining S-Video devices.
I would also recommend purchasing a harmony remote to manage all of these devices... they may seem expensive but I found it to be money well spent. the 360 specific remote is quite nice because it's the only one with ABXY buttons making it handy when using with consoles such as the PS2, PS3, Xbox 1, or Xbox 360