I was able to locate manual and a troubleshooting guide.
- Troubleshooting Guide
Summary: Your modem only supports 802.11b standard, which limits the
throughput to max. 11Mbps (compare to 802.11g = 54Mbps, 802.11n = 108
Mbps). In other words: your connection is only about 10% of the speed
compared to a wired connection via Ethernet cable (100 Mbps). So - if
you can - you should try to use a wired instead of a wireless
connection, but you have to decide what makes is more important to you:
having no cable and you can be away from the modem or the connection
This also means - and that is in regards to APremkumar's solution -
that you can skip all 802.11n adapters (this would just be a waste of
money). Since you will not find an adapter that only connects to a
class b network, look for something like "802.11b/g".
An example page is here
You can choose between an internal (PCI card) or external (USB adapter)
solution. Both are ok and the decision depends on the availablity of a
free USB port on your Dell and your comfort of opening the computer
case or not. (You can always come back here and ask for help;-)
If you have any more questions, please let me know - I'm happy to help!