Actually , Avast is the first antivus in the compatives.(largely better then McAfee , that's sure ^^ )
Antispyware , to complete the Avast's work I suggest a complete scan with Malwarebytes every week after updating it if you don't take the Pro version ( which updates itself in realtime if you select it )
and if we get rid of this malware what tools would you suggest to stop it coming back?
There's no tool to stop it , just to clean it
( If there's still Ramnit infection in the computer, ok ?)
the better thing to do is having all the softwares updated ( in priority Windows , your antivirus , FlashPlayer and Java if it's installed for the last cause if none application needs to have Java installed , It is not compulsory to have it in your computer , it's not a "windows" native program , the computer can work properly without)
for Mcafee I'll give you their special tool to completly delete the pieces of it which could rest in your computer