PC Audio & Headset Shopping: Help Wanted

So my cheap $5 headset is finally dying on me after several years and I need to replace them. I'd like to get something fairly nice, but can't really see myself spending a ton. I think I'd prefer to not go too far beyond $100. This would be primarily for gaming, but also for movies, streaming video ( I <3 Hulu ), and music.

I'm looking at this Steelseries as well as this ATH-A700.

I've also seen suggestions for the Sennheiser 555 and simply adding on a Zalman clip mic. The Senns go for $105 from Amazon.

I've also seen a Medusa 5.1 Headset, but I've seen reviews both ways on it.

If I could get a decent 5.1 or 7.1 set that worked well and didn't cost an arm & a leg then I'd consider it. The Razor Megalodon is a 7.1 but is USB and is a bit more than I'd like to spend and seems to have some mixed customer reviews on Newegg (although complaints do in part seem to be due to lack of user competence in setup and use of Win 7 OS).

Additionally, on the sound card side: I've got an old SB Live Value 5.1 PCI card. The board I've got has a 7 channel onboard that I don't have installed, and I'm considering a new build that would put me with a mobo w/an 8 channel Realtek onboard audio. I know that onboard options are greatly improved over yesteryear, but stand alone cards can still provide increased quality.

I've seen suggestions for several discreet solutions such as:

AuzenTech AZT-FORTE X-Fi Forte 7.1

As well as the ASUS Xonar DX or ASUS STX Essence.

If anyone has any thoughts/personal experience(s)/recommendations, I'd love to hear them.