well if its completely removed then the only way it is coming back is if you repeat the thing that got it in in the first place and you said you'll be more cautious this time and not click anything stupid so thats good.
update norton, do the full scan with norton it should find anything remaining in the system. norton has a fantastic malware prevention system, it has this thing called SONAR which is a behavioural analysis blocker and it works extremely well in most if not all tests i have seen it has blocked 98-100% of threats thrown at it. no internet security suite or antivirus gives 100% protection but norton is one of the best internet security suites out there right now, along with kasperksy, bitdefender, eset to name a few but from what ive looked into norton has really stepped it up recently...the free software like avast is good, good detection rates but im afraid norton beats it in terms of prevention and i would go and say better detection (but obviously you have to pay which can be a bummer to some people) but some free software are also good like avast or avira.
just to be on the safe i would post on the forum with the hijackthis log so they can analyse and see if anything else remains but if you do all those things i told you i would imagine most if not all of it will be gone from your system