Not a good idea. The repair-ability depends on the type of infection. Viruses are less common and it's possible that the infection might be something more serious.
Sure, you can pop the infected hdd into a HD case and run an av/anti-malware software on another laptop. But you do risk the infection spreading to the new laptop. Keep in mind that there are different types of infections that may not be cleaned completely by avast or any similar solution. The safest approach is to wipe the infected hdd completely and start from scratch.
Alternatively, AV/anti-malware vendors usually offer some sort of LiveCD/PE functionality where you can use a CD/DVD/USB to boot into a known clean OS image. From this point, you'd generally run the AV/anti-malware scrubber to hopefully remove all traces of the virus/malware/trojan/spyware/etc. This is probably your best bet because you can confine the infection while you try to remove the infection or retrieve/backup data.
If you have data stored on the hdd you can't lose, then I'd recommend consulting a data recovery expert.