Some IT roles in an organization are;
- business analyst: person who analyzes the business systems and finds solutions to problems
- system analyst: IT personnel who manages business applications
- web applications developer: IT personnel that deals with developing internet based applications and managing them
- Help and support: Offers advice to customers or users who have problems with computer equipment or systems in an organization. These IT people are usually very important.
With regard to equipment and all for like a business analyst they will have a work station with there own pc. Now organizations also have databases for warehousing of all there organizational data which are also backed up (usually at another location), there are also at times large networks that are setup within an organization, like large servers that network all organization units and locations together and also to the internet. There is also security measures for the machines, such as the use of firewalls both hardware and software wise to effectively protect the data from intrusion or corruptions.
These are important because the organization cannot effectively run its business because they are these days reliant on the use of IT to effectively manage there data, facilitate communication amongst the organization internally and externally.
Please note this is my personal response.