seeing as you have old 11b now , id go directly for all 11N kit and bypass the old 11g as you can then be reasonably sure the 11n will manage the up and comeing VM 50Mbit down/1.5Mbit up connections better.
remember 11g gives you a real top throughput of 22Mbit
at BEST, averaging 15Mbit/s or even less with all the security turned on that many internal routers CPUs cant handle at the advertised full speeds.
all the 11n can manage better data throughput even when in 11g mode due to them having a better internal CPUs/SOC that can better handle the software settings you might turn on.
keep in mind those belkin were in a class action in the US for many models having to give back a 100% refund due to this lower spec CPU not giving the advertised speeds and other related side effects.
SmallNetBuilder. is a good place to read up on it all when your Belkin starts playing up later