Here are the basics. 802.11a was used only by big organizations with their own LAN's. The first consumer wireless routers were 802.11b models which transmitted and received up to 11 Mbps. Then came the current adopted standard 802.11g routers which send and receive at up to 54 Mbps (hence the commercial shorthand of them being '54G' routers). There has been issued RFC 802.11n as a draft standard. RFC stands for Request for Comments. N routers have up to four times the speed and three times the range of 54g routers,
Until a final international standard is adopted there is some risk that any hardware one buys could become obsolete if the adopted standard is so different than the draft standard that the old equipment won't work with the new equipment. The industry is betting that any changes adopted in the finalization of the standard will be minor and peripheral and that their equipment will continue to work. In practice it doesn't matter to you at all. If YOUR receiver will receive YOUR router, what do you care what standard is finally adopted by the industry?
Most computers come with 802.11a/b/g receiving capability built in to them. Recent ones come with 'n' receiving capability built in as well. If your machine does not have a receiver built in, or it receives a lower standard than you want, you will have to buy a separate receiver that will plug either into your USB port or your pc card slot. For reasons of tradition and basic reluctance to use comprehensible English, these plug-in receivers are called 'adapters'.
As to specific makes and models it is good to "ask the man who owns one". The best place to look for this kind of information is the user comments in Amazon.com . Look up the product and read twenty or thirty of the comments and a consensus will appear. I had assumed I would get a Linksys router and that checking the user information was something of a formality. Linksys is made by Cisco, a giant in the industry and thus basically the standard router, providing reliability and utility at a reasonable price compared to its competitors. At least on the 54g routers, On the N routers, the customers were screaming that they just didn't work no matter what they did to configure them. Customer support was inadequate, seemingly because the underlying problem is that the routers are no damn good. The anger and frustration was palpable. Nobody had anything to say one way or the other about the Belkin N routers. They plugged them in and they worked, which nobody found noteworthy.
As to your current router -- if it has one or two antennae on the back it is both wireless and ethernet. If it doesn't it is ethernet only, I know of no way to make an ethernet router into a wireless one, Ethernet (the wire connection using what looks like oversized phone jack connectors at the ends) runs at 100 Mbps, almost twice as fast as 802.11g wireless, but not as fast as 802.11n wireless,
Sadly one is not free to ignore the advance of router speed. Website writers are aware of the speed of most routers and they write websites correspondingly to include ever-bigger files. I suspect the optimum balance between cost and performance is to get the most standard and conventional. My notion is that buying bleeding-edge hardware is probably a waste of money. The N standard not having been adopted yet, it would qualify as bleeding edge. B is outdated and will become more so and is also a waste of money, My suggestion would be to get a Linksys 54G, It's relatively cheap and works with no struggle. If you are connecting a desktop, you can get a pci card receiver-adapter. If the desired receiver is not built in to one's laptop, one can get a receiver-adapter for the USB port or pc card slot as I mentioned above, but almost any current laptop will have at least b and g receivers built in.