Unknown program found in add/remove programs

I was looking/reviewing proram installed in PC I got a new PC 3 weeks ago - found "HiJack This" and never downloaded it. This made me very nervous to have a proram installed without my knowledge. New PC is an IBM running Windows XP as operating software(1st time experience with XP) I am having a hard time learning this software.
Not so sure that I am not current with virus protection. I currently have Symantec AntiVirus Corporate Edition - Version is 8.1.0.825 installed and it is set for real time protection. Also have the Microsoft Beta version of Anti Spyware
Prior pc used McAfee and felt it did a good job.How do I confirmthat I am truly protcted from all of the "stuff" that keeps coming towards my pc. Afraid that one amay have slipped into the hard drive. Data on my machine is important very important.

You have nothing to worry about. Symantec does put a heavy load on your PC, and personally I would not touch it with a barge-pole. But since you have it, as long as you don't have to pay for it, keep it.
When it comes to renewing though, let us know, we have some good, free alternatives.
HiJackThis is a program that you WILL need if you ever get infected. It's only small, so just leave it.
Go to www.getfirefox.com and install Firefox. Use that exclusively from now on, and use IE ONLY for Windows-updates.
And replace Outlook Express with Mozilla's Thunderbird from http://www.mozilla.org/products/thunderbird/