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.

I have my eye on this
http://reviews.cnet.com/routers/d- [...] prod.txt.1
and
http://reviews.cnet.com/routers/d- [...] prod.txt.9

any advice or recommendation will be well appreciated

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/