So here's the situation, it's going to be in an office connected to 5-7 computer/laptops + an old macbook running 802.11b (probably), and they are usually transferring data to a main computer as well as sharing internet. Which router would be most reliable, safe, and fast. Range would be an asset but not super important.
Would suggest you do some research starting with this site given this is for a business. In addition to what you have listed you didn't list one of the most important things, which is security. Not sure paying extra for wireless n right now makes sense given the final standards haven't be set. I have a ZyXELL X-500 and have had up to 6 computers and a Play Station attached with no problems but still given it's for a business I think some more research would be a good idea. Your also may want to look at storage and sharing either with a server or NAS, if not right now, probably in the near future and you'll want something that will work with these as well http://www.smallnetbuilder.com/