Intel 5100AGN - 3Com Router, Problem

I'm abit of a novice when it comes to networks (hence why I need your help actually).

Recently Purchased a Dell Precision M4400. Vista Business 64-Bit.
(Nvidia FX770M Gfx card, T9600 Processor)
In the Network Adaptors heading of the Device Manager there are two devices:
Intel(R) 82567LM Gigabit Network Connection
Intel(R) WiFi Link 5100 AGN


Have a 3Com "OfficeConnect ADSL Wireless 11g Firewall Router" Says this on the front of the router aswell "3CRWDR199A-72".
On the sticker underneath is "Model: WL-542

Currently using WPA-PSK, TPIK, Encryption.
although the problem persists when encryption is disabled.
Went to the Intel site to get the latest drivers but this hasn't helped.

My problem is that if i try and connect to the router from anywhere but standing right beside the router then it will not connect.
Also although it says the signal strength is "excellent" it only has two out of 5 bars on the Dell Connectivity Manager icon on the taskbar.

Settings of the Adaptor are
802.11n Channel Width for band 2.4: Auto
802.11n Channel Width for band 5.2: Auto
802.11n Mode: Enabled
Ad Hoc Channel 802.11 b/g: 1
Ad Hoc Default Wireless Mode: 802.11b/g
Ad Hoc Power Management: Disabled
Ad Hoc QoS Mode: WMM Disabled
Fat Channel Intolerant: Disabled
Mixed Mode Protection: CTS-to-self Enabled
Roaming Aggressiveness: Medium
Throughput Enhancement: Disabled
Transmit Power: Highest
Wireless Mode: 802.11a/b/g


Any help would be greatly appreciated.
Thanks in Advance.

 

You may wish to see if there's a firmware upgrade for your router.