Question about identifying Linksys WRT54GS version

Hey guys, I know this is a pretty weird question, but I was wondering if any of you knew how to identify which version of the Linksys WRT54GS I was using. I threw away the box, (oops - noobish mistake) and I can't seem to find anything about identifying your router version anywhere on the internet. In case you're wondering, the reason for this strange question is that I want to get onto Xbox Live, but after purchasing the Wireless Adapter and opening it, I realized I didn't have a compatible adapter I figured out that the Xbox and it's Wireless Adapter only accepts the WRT54GS Version 2, and on the firmware section of the Linksys downloads site it says that there are 6 version of the WRT54GS, so PLEASE HELP ME, ANYONE! P.S. the Xbox Live diagnostic test says that I'm failing the MTU Test, can anyone make heads or tails of this?