Hosting question... What line do i need?

Take a look at:
http://www.threehosts.com/reviews
or
http://www.threeehosts.com/business

GL!

If you and your company are new at this, I recommend you guys consider hosting it with a hosting company first. Look for dedicated or VPS hosting. This way, your hosting company will take care of the server, router, network for you, you can learn from the stuff they do/use and I am not sure what bandwidth packages your ISP offer, but I know bandwidth is so inexpensive nowadays that most web hosts offer a lot more at a lot less than your ISP.

It depends how big the business is. ADSL might actually be fine, if it's a small business. We need more info. Also, consider whether you really want to host it on-site. Off-site hosting may be cheaper and more convenient.

Note: There is no rule that /all/ ADSL services are only for home customers, and again, there may be enough upload bandwidth if this is a small business.

Well, you don't want to use the ADSL line, since your provider won't let you host a server on it (it's in the Terms of Agreement). Besides, the inbound connection won't be very fast, so your customers will have problems getting to your site. (ADSL is designed for fast downloading by homes users).

Check with your service provider and ask about "business class" DSL. That will be faster both ways, and cheaper than a dedicated T-1 line.

If you do this, you're going to be exposing yourself to the outside world, so you need a quality firewall device and a router that can handle the load you may get, as well as your network's outbound needs. The firewall is critical in keeping bad stuff out, so you don't want to go cheap. The SOHO routers like the little netgears and linksys units are too small for this kind of activity.