|For later, when you've done Revo (again??):|
As Nod isn't a virus it should not be hidden in any big way. If the remnants are what is bothering you then they can only be due to one or more of the following:
Last first - I don't know whether Nod invokes a service, although it is unlikley. However it should not be too hard to find one if it is there. After all, you seem to have dabbled with computers for years.
Files must be somewhere and an appropriate search should find them, ie Eset and then Nod. These are best removed before tackling the registry.
Registry entries, well if you want to be safe then use CCleaners Registry feature. I don't usually advocate registry cleaners but CCleaners is as safe as any. Just let it remove only those entries which are clearly due to Eset Nod - untick all the rest.
Always pop back and let us know the outcome - thanks