Depending on how big your business is, there are things that any entrepreneur needs to buy to make a business successful. One of the first things, for most businesses, is a robust computer system. HP is highly recommended, because of its sophistication and attractive bulk prices. You can even get discounts if you are using HP coupons. You can use HP computers in a networked manner using Linksys or Netgear routers to effectively collaborate across rooms.
One other important thing you may want to invest in is a high quality printer. Every office needs a laser printer at some point of time. Once you get the printer, think of a photocopier, if you think that would be useful. Get good videoconferencing systems if you are dealing with multiple locations or need to talk to clients long distance.
Apart from hardware, there’s a bunch of software that can be useful. No business can do without a good accounting or tax software. Intuit is a good one; Quickbook Pro is also good for the small office.
Small businesses need to focus on how to use open source or freeware to keep costs down. One good way to collaborate online is to use Skype. This is a VOIP telephone system that also lets you chat and collaborate online. Businesses that deal with employees online can find this very useful for collaborative work. International businesses, dealing with long distance clients, can find this very useful.
There is not really a hard and fast rule about what you got to buy to be successful. It kind of depends on what you are selling. But in general, you should never shy away from spending in those things that improve business communication, whether it is with clients, or with business personnel.