http://www.napoliunplugged.com/

The archeological museum is world class--a must see.

Archeological museum --where about is it in relationship to
Napoli Centrale Station please

At a rough guess, around a mile east of Piazze Garibaldi (and the station). It is only about 200 metres from the Pizza Cavour metro stop.
If still available , the all day GiraNapoli card is very cheap (<€5) and really useful as it covers metro, buses , trams and funicular railways.

Other things I love to do in Naples include:

Taking the Funicular up to near Castle St Elmo. Not much in the Castle itself, but the views across the city are spectacular.

Walking the length of Spaccanapoli (I particularly love the shops selling characters for "presepe" Nativity scenes.

I agree with the sites mentioned so far. I'd add the lovely courtyards of Santa Chiara church & monastery. And if you're going up the hill to Castle St. Elmo, go ahead and explore Certosa di San Martino as well. And enjoy some classic pizza at Sorbillo.

If you had more time, I might recommend the Subterranean Naples tour... although it might not be for everyone, especially those predisposed to claustrophobia.

Actually, my #1 recommendation is to get a good map and study it.

Enjoy!

If you are going to Naples and Sorrento, I suspect you may be including Pompeii and/or Herculaneum and may be in the area for a few days. There is a 3 day ArteCard for the region that would cover transportation including the buses and the Circumvesuviana to Sorrento from Naples and points between, as well as the naples subway, two free admissions to sights, and half off the rest. You can buy it at the Naples RR station (cash only). It is well worth it.

Pompeii for a day then Herculaneum for a day but am thinking I need more time
in Naples so after I go round Sicily clockwise from Catania to Palermo I may given
enough time go back to Naples before crossing the Adriatic for rest of my journey

Herculaneum is at most a half day, and probably less. We combined Pompeii and Herculaneum into the same day, doing H after a long morning in P and after a latish lunch. The next day we did the archeology museum in naples, which made for a great sequence: Large ruined city, reconstructed city, art details. The 3 day arte card covered 2 1/2 admissions and all the transit (we were based in Sorrento).

You can easily walk from the Capello San Severo up the hill to the National Archeological Museum, I don't think it's more than a mile. They offer one hour tours of the museum which could be fun as you have lots of time. If the "Sectret Room" of erotic art is closed just ask at the front desk and they will open it up for you.

I agree Herculaneum is no more than a half day but can be combined with Opolontis which is in the same town. We really enjoyed seeing one of the Roman villas, it was much quieter and gave a real sense of the lifestyle and domestic architecture of the wealthy.

If I got early train to Pompei would I have
time to see a good bit of Pompei then go
to Naples for more sight seeing one day
And would I be able to do same thing with
Herculaneum & Naples the next day
Thanks if some one can advise!!!

It is more efficient to do Pompeii and Herculaneum on the same day as they are near each other by train. Then use the other whole day in Naples and save the travel time. Also, if the weather is good one day and not the other, use the good weather for the two outdoor sights.