Depending on what the hacker is using to gain access is waht he sees, most of the time it is a simple command line, noen of these flashy graphics you often see in the movies.

There are MANY ways that a hacker can gain access to your computer, the things you need to worry about is having an up to date virus scanner, and probably a decent firewall will help out too. Try to keep your operating system as up to date as possible w. system updates, and read up on newsletters such as the ones on security focus about new threats.

good luck.