Realtime antivirus and antispyware scanners together?

There are so many "suites" around these days but I run Avast antivirus as my only "realtime" scanner for Win7 64bit.Years ago I used to use a realtime antispyware scanner along with an antivirus and well nothing seemed wrong but what about nowadays?Is there something I can use to augment Avast in realtime as well without conflicts or heavy performance hits?
I don't like "two in ones" or "security suites".

I just use Avast in combination w/ Windows Defender, and have never had any problems since running Win7. BTW there's a new pre-release build 5.1.874 of Avast available (includes fixes for current release 5.1.864), which is what I've been running...

http://forum.avast.com/index.php?topic=68927.0