Should we change wireless protocol in our office? We have A, most new laptops don't read A.

Most routers today have support for A/B/G. I wouldn’t bother with N if you don’t need the speed.

B is the most common and you should at least be able to support that.

Was your tech-consultant hungover when he gave his opinion? :P

It may be just as cost effective to go with N, which is fully backward compatible, so that you have the headroom for future developments, even though you may find yourselves using primarily B or G for the moment.

A is for Ancient, B is for beginning to get too slow, G is for good for now. N is for next. We migrated from A quite a while ago, but it was really easy, We had mostly Orinoco routers so just had to swap out cards. Going to N will require new routers, but we got a lot of mileage out of the old ones.

It would probably be less expensive to get a new G or N access point than getting A cards for the new laptops. Also, the A cards would be external, easy to lose and they clutter your office.

If you do go with G, I recommend a MIMO access point for better range. MIMO is built into N, it’s optional with G.

I suggest you get a new tech consultant.
802.11n is a much better option. The signal is much stronger and you are capable of higher transfer rates. Also, with most n based routers you can run g at the same time to support older devices. Most new laptops have b/g/n compatable cards, so why not go for the best and most scalable option?

I would go with G. If your buying a consumer router then its easy and cheap to get one that has G and N. Also G is backwards compatible with B and N routers also support G.