Windows Defender - should I or shouldn't I?

I hope this is the right group to come to, if not, please redirect me.

Please can someone advise me.
A friend told me I should download Windows Defender. I know very little about p.c.'s so would like to know what Windows Defender does and whether I should download it?

Many thanks.

Relevant Pages

  • Re: MSN Virus
    ... | My computer has been infected by a virus spreading around by MSN ... Windows Defender detects it at startup ... I suggest scanning the system in Safe Mode. ... FireWall to allow it to download the needed AV vendor related files. ...
    (microsoft.public.security)
  • Re: Explorer Window Hangs / Process doesnt end
    ... then run HiJackThis and post ... This may be caused by spyware/malware that's gotten installed on ... Windows Defender and/or Spybot Search & Destroy ... Also download a winsock repair tool, to have just in case cleaning up ...
    (microsoft.public.windows.inetexplorer.ie6.browser)
  • Re: malicious software removal tool
    ... do a system restore to get them back. ... Distribution Service 3.0'. ... have accepted an EULA to download and run something called Malicious Software ... Yesterday however I did download a Windows Defender ...
    (microsoft.public.windowsxp.security_admin)
  • Re: KB915597
    ... downloading updates at least as far as updates for Windows Defender is concerned. ... It is not much of a problem because I think that Windows Defender is not really that great but, it is free and probably does no harm. ... [CallerId = AutomaticUpdates] ... to 'Download Approval' ...
    (microsoft.public.windowsupdate)
  • Re: IE so sloooow
    ... Connection Speed Test showed Download Speedup to 494 kps, ... Windows Defender and/or Spybot Search & ...
    (microsoft.public.windows.inetexplorer.ie6.browser)