High Speed Internet/Equipment?

Hi,

Got a couple of questions, we are looking to install high speed internet at work, either leased line, dedicated ISDN or broadband connection or ADSL.

Ive searched google to find a comparison, but cant find anything. Apart from speed are there any advantages of 1 over the other? Also we are considering wireless internet access, what components would be required, just a wireless router and network cards, would it be possible to have 1 router for around 55 rooms?

Any help/information would be very much appreciated!

If you are hosting servers ( ie web server or mail server ) or connecting remote sites via VPN I would get a dedicated leased line T1 perhaps because of the stability and upload speeds, also blacklisting is getting common for having an IP address in a dynamic range which is common on cable connections. For cheap connection I would use ADSL as the bandwidth is dedicated you are not sharing with everyone in your neighborhood like cable, upload speeds are usualy 256k-368k though. Cable is fine for just internet access. ISDN is very expensive and very slow so throw this idea out the window.
I could elaborate on each of these but Im not writing a book.