Check the "advanced" settings by pressing the menu button in the wireless and make sure nothing wierd is set in there.
Otherwise, as long as the router is set to N only on the 2.4ghz band, it should at _least_ see the SSID.
That modem supports WPS, try pressing the WPS button on the back of the modem and then use the "WPS button connection" option in the wi-fi settings menu on the SGS2.
Remember the single-channel 802.11n 2.4ghz such as the SGS2 supports will only max out at 72mbps anyway so there's not a huge improvement over the 54mbps that 11g will give you, although 11n is more efficient.
1) There is NO SUCH WORD as "alot" - It's "a lot"
2) The shortened form of You are is You're - NOT Your
3) Loosing & Loose have completely different meanings to Losing & Lose.