Windows Vista-compatible alternatives to Yahoo Anti-Spy?

According to a resolved question in Yahoo Answers, Yahoo Anti-Spy is currently incompatible with Windows Vista (which explains why I couldn’t get the Yahoo Anti-Spy button to display on Yahoo Toolbar on my new computer with Windows Vista). What would be the best Windows Vista-compatible anti-spyware program to use instead of Yahoo Anti-Spy? (Norton Internet Security has a free trial version preinstalled on this computer – but after all the trouble I’ve had in the past with Norton bollixing up my use of other legitimate programs (such as eBay’s Turbo Lister and Avast! itself), I want to avoid using Norton if at all possible.) Free/shareware anti-spyware programs would be preferred, as it’s a 20-30 minute drive to the nearest Wal-Mart, and more like 45 minutes-1 hour to the nearest office supply or electronics store.

Well avast 4.8 is now detected by Vista Security Center as an anti-spyware.

SUPERantispyware On-Demand only in free version. Or Spyware Terminator Resident scanner (if you use this don’t install the toolbar or crawler or the anti-virus module).

I wasn’t aware that Avast! 4.8 included anti-spyware protection, but that’s what Alwil’s press release about it (read elsewhere on this site) says. Apparently, after I had copied Avast! 4.7 from my previous computer, when this computer downloaded its first update to the Avast database, it must have installed Avast! 4.8 also (I noticed the slightly different appearance when I tried to run my first scan). Do you have to do anything specific to scan for spyware with Avast, or is that just included when one does an antivirus scan with Avast? (I didn’t see it specifically mentioned in the descriptions of the On-Access Scanner providers.)
If anti-spyware protection is indeed included within Avast, though, then I’m not so worried about not having Yahoo Anti-Spy’s button available on their toolbar under Windows Vista.

It is integrated in to the regular on-access and on-demand scans.

I would still recommend SAS as a back-up anti-spyware scanner, the free version is as I said on-demand only so shouldn’t add any load to your system until you run a scan. The free version doesn’t have auto update (like avast) so you have to remember to periodically update it. I do a scan once a week with it and just before the scan download the latest updates.