Which antispyware is worth having?

I'm contemplating new antispyware on my XP-based system. So, which of the following do you consider the best overall solution for longterm antispyware?:

PC Tools 'Spyware Doctor'

Spybot Search & Destroy

Webroot Spy Sweeper 5

Windows Defender

Anyone any idea how much the annual subs (in £ sterling) for Spyware Doctor and Webroot Sweeper are? I tried contacting the originators but they won't tell me. I don't mind buying a piece of software (given that it's reliable) but I baulk at paying out annual subscription fees.

Spybot and Defender are both free but I've heard that Spybot is buggy (especially with IE7) and that Defender has only very limited capabilities.

Here is what I use on all my boxes, and why I use a suite of tools as well:

Spybot - Search & Destroy, reason, it's my main Anti-Malware app and their forums for spyware removal are very good indeed. The immunize feature is great for blacklisting sites under the Restricted Sites Security Options.

AdAware PE, reason, it's my secondary Anti-Malware app.

Spyware Blaster, because they update a lot and it overlaps the blacklisting for the Restricted Sites Lists. Some things this app has that Spybot does not and vice-versa.

Spyware Guard, mostly to see if any other weird IE vectors are attempting to be exploited or not.

I used to use the Microsoft Anti-Spyware, but I think I was just duplicating the same features with AdAware and Spybot.

For free I use the AVG Anti-Virus app for my email and it supports Outlook 2000, which is more then what I need for an email client

Thanks for the feedback.

Just how buggy is Spybot S & D, though? When I looked at the Spybot forums, I was really put off by the numbers of different bugs it seemed to give rise to. Does Spybot fully support IE7, for example?

Spybot would ne nice to have, since it's free, but by all accounts it seems to miss a lot of important spyware. So, I keep wondering whether it'd be better to BUY a package - like Webroot Sweeper or Spyware Doctor - which would give more extensive cover.

Can Spybot scan in ANY part of the PC? I find that the free version of AVG Antivirus, for example, does not scan ALL areas of the hard drive, even if you point it to specific areas. It won't scan for folders in My Network Places, and that's where some nasty spyware can lurk. Thus, whatever I use for antispyware will need to be able to scan in all folders and subfolders of My Network Places, beside all the usual places.

I use the Windows Defender of Vista.
I think it's not perfect, but I dont wanna install other program, because of it's an adjunct of the Windows.
Maybe the compatibility also need to consider.

Use IE7Pro
Enabled Ad/Flash blocking in IE Pro.
Never click on any ads or popups.
Make sure your not running with Admin rights.
Install spybot and Immunize your system. (Blacklisting isn't that great but when it blocks thousands of sites it does help a little).
Use common sense.

In summary the best antispyware worth having is yourself.