There is a lot of guidance for you to read below, please do not see it as a lecture as the information that I have provided explains how a couple of minutes browsing the internet for a new pair of shoes can have dire consequences.
Yours is a difficult question to answer with 100% certainty, this because we have no knowledge of what the arrangement is with the company that employs the staff there and the personal use by employees of the computers that are provided for work purposes, the general rule of thumb is that the computer and all of the data that is kept on any storage device connected to the said computer is and remains the property of the company until the computer/s and the data stored on them are disposed off through means that the company will have in place.
As you have an IT department there will be an authorized person who has overall responsibility for the computers and the accepted use of them, in a work place environment this person will be the overall System Administrator and I am sorry to say that unless there is documented proof that you are allowed to use the computer for personal use which may include personal data being stored on the HDD which will remain accessible by you alone by being password protected, the System Administrator can access any computer at any time with impunity, apart from the regular maintenance of the computers and the system software that is what the System Administrator is employed for.
Other considerations are the fact that as your computer is part of a network it can be accessed remotely without you knowing about it (even when you are working on it) that the company that you are employed by will be paying a considerable amount of cash for internet access and they may not take too kindly to employees adding to that cost and finally heaven forbid that it should happen your computer could become infected by malware while you are on the internet (even ebay and FB) and this has the potential to corrupt the whole of the companies computer network.
Unless you have the written permission to use the computer for the personal use that I mention above I would strongly advise that you use the computer/s for nothing other than work duties, if you do have written permission that covers personal use which may include personal data being stored on the HDD which will remain accessible by you alone by being password protected, you should approach the System Administrator and inform them of your concerns and have them look into it, if the IT officer that you mention in your OP happens to also be the System Administrator then follow procedure and speak to them first and if the situation is not resolved to your satisfaction you should take the matter to your immediate superior and have them take the matter up.
Finally, keep in mind that if you use the computer for nothing other than work you will have no need to worry about "your intimacy" as there will be no personal information on the computer and last but not least, inappropriate use of company equipment and paid working hours can and most often does result in disciplinary action being taken against the employee/s concerned.