As you are on xp you need to go further than would be normal as far as security measures are concerned. Windows xp is no longer supported and hasn't received security patches for over a year now, so it has vulnerabilities, and internet explorer on windows xp has even more vulnerabilities.
You need not purchase an antivirus there are atleast 3 good free ones:
avast, bit defender free and avg. Do not delay in getting one set up. Bitdefender free is the one with the least bundling problems, but it desn't give you many ptions with it's settings. Avast doesn't have severe bundling and works wel, but will give regular little "have you heard about or business editions" pop-ups in the bottom right corner. AVG has worse bundling (they try to get you to install an optimizer tool, don't do this ever) but is also quite effective.
You will need more than just an antivirus:
an antimalware program like malwarebytes is a very wise idea, there is a free version for on demand scanning
You will need a third opinion scanner as well:
ESET online scanner is good for this
You will need to ditch internet explorer:
firefox and chrome are both still available for XP, both are kept up-to-date and secure.
You need to keep any plugins up to date, and keep up to date whichever browsers you have and whichcever antivirus you choose.
You need to back up your data regularly.
You need to run a scriptblocker in your browser, with xp being vulnerable you need to do everything you can to make drivebys impossible. Gone are the days when you would only get a virus from malicious downloads or shady sites, they can come from anywhere these days, often via adverts. NoScript in firefox is good for this.
You need to make some system images, on later windows operating systems there are functions to do this built in, on XP there are not so you must use third paty tools such as macrium (there is a free version).
You might want to run some sot of whitelsting program, there are several which describe themselves as being for preventing crypto ransom infections but they should prevent other viruses executing as well.
You likely want to run extra protection against exploits alongside your antivirus, antimalware, script blocker, up-to-date browser and up-to-date (deactivated where possible, "click to play"/"ask to activate" otherwise) plugins. This could be done with something like malwarebytes anti-exploit, an extra anti drive-by layer behind your browser and infront of your antivirus and antimalware.
The good thing about NoScript, malwarebytes anti-exploit and whitelisting programs is that they stop new viruses, not just ones in an existing database by working on a principle of "block unless the user says let it through" rather than "allow unless it matches a known nasty in the database".
Note that a day will come when neither these antiviruses nor chrome or firefox will be available in versions which can run on XP, when that day comes you will need to move to windows 7, 8, 8.1 or a linux operating system. Until then you just need to take as many steps for security as you possibly can.
Edited by rp88, 24 May 2015 - 09:50 AM.
Back on this site, for a while anyway, been so busy the last year.
My systems:2 laptops, intel i3 processors, windows 8.1 installed on the hard-drive and linux mint 17.3 MATE installed to USB