Just to clear up some confusion over geographical and political definitions.
Manchester is a city so there are no towns inside it per se. The places listed by Blakefish80 are suburbs of that city - ie within the politcal borough.
Many others listed tend to be considered to be in Manchester due to the close proximity, but come under different politcal boroughs, such as Trafford, (which is where Man Utd ground is situated - so technically it's not in Manchester !). If you lived in the borough of Trafford, and were speaking to someone not from the area you'd probably say, genrrally speaking, you were from Manchester nevertheless.
Other places on the initial list, such as Wigan, Rochdale, etc., are towns in the metropolitan county of Greater Manchester (created in the 70's; prior to that Manchester was in Lancashire. Some of the other places were in Cheshire). Residents would typically say they were from the given town name rather than Manchester.
Salford is actually a city in its own right - but again, right next to the City of Manchester.
If you simply want PLACES that are geographically in the county of Greater Manchester, regardless of the political boundaries and definitions of what is a town and what isn't, then the intial list is good although some, such as Stockport, are in Cheshire.