Purchased a second-hand PC, but Windows XP installed is not a pukka version, what to do?

I bought a used PC on ebay a few weeks ago, I've been really happy with it, but yesterday tried to get the latest version of Windows Media Player, and it wouldn't install, saying my version of Windows XP was not genuine. This is annoying, Microsoft offered to legitimize the version I have for 拢95 (more than I paid for the PC).

My question is, how much of a problem is it not having a pukka version of XP Pro? I can't install any updates for any Windows products, but is this the end of the world? I have anti virus and firewall software, so I should be ok security wise right?

Purchased a second-hand PC, but Windows XP installed is not a pukka version, what to do?virus protection

This topic has good and valid arguments on both sides. Some would say keeping your windows up to date is essential in keeping it free of the newest, worst viruses and the like. Others would say that updating your windows is overemphasized, unneeded and a waste of time.

In the future, Microsoft will have ways of detecting whether your version of windows is actually store-bought, or pirated. With so many copies of pirated windows on the market, such a move by Microsoft is almost required in order to continue cornering the OS market. For instance, when SP 1 (and 2) came out, you had to have an authentic windows serial code in order to download the update. There are of course ways of getting around this, but it deterred much illegal upgrading to the new service packs. Had you have had a pirated copy of windows (and the majority does), then you could have downloaded a copy of windows SP 1/2, but you would have had to completely re-install and possibly format in order to install it.