Setting Router Usage & Access Priority? (for slingbox)

[Ferra]

I have a slingbox in my house that my gf&family use to watch TV in their home.

However, everytime they use the slingbox, my my network becomes very slow, and it makes gaming nearly impossible (500 ping)
Surfing and downloading is fine tho.

So I was wondering if it is impossible to set the slingbox access to the lowest priority, so that it doesn't affect the gaming speed when someone connect to the slingbox. (I don't mind the slingbox having a lower stream speed & lower quality)
I have a 25Mbps/1Mbps connection and I think that should really be able to handle both gaming + slingbox

Is this something easy to do? What kinds of router and firmware is needed? (I have a Linksys 160N running original firmware)

[!MiKrofT]

Check to see if you have QOS (Quality of Service) settings in your router. In addition maybe bandwidth limiting on the Slingbox's IP? Although I'm not sure most routers have the 2nd option.