you will not notice the difference between 54G and 108G Karen the speeds are 54MBs and 108MBs respectivly (MBs = Mega Bits per second), the fastest broadband connections are only 10 MBs and most internet sites cant manage 1 MBs.
If you can get a good deal on a 108G then go ahead but unless you plan on having a dozen wireless pc's and have a super fast internet connection i doubt you will ever make use of the bandwidth.
I have a Belkin Wireless Router and cant complain, it has a reasonable firewall built in and allows me to restrict the access times (my eldest would be up all night every night if i didnt) it has no facility to restrict access to 'suspect sites' or log access, but this is not a problem for me as far as i know!
I have used Dlink and also a linksys products in the past and i cant say that any of them stands out above the others they all have their good and bad points. Make sure to get an ADSL router if you connect via your telephone line or a Cable router if you are on cable internet.