Depending on the size of your library and the depth of its technology needs, contracting with an IT services provider can be more cost-effective than hiring a library IT employee. Libsynergy and PC Solutions Plus are two examples of IT service providers.
Hiring an IT manager can reduce the burden on your staff and ensure that your systems are running smoothly. Laura Solomon of the Ohio Public Library Information Network has an excellent series of posts on her blog called How to hire a library tech. To summarize, the most important qualities in IT staff are the same as for regular library staff: flexibility and excellent customer service skills. Technical skills can be acquired as needed.