When choosing a dust collector for your circumstances, you need to understand how a system works and how to calculate the air velocity, air volume and static pressure that you will need. Again I would recommend the book by Sandor Nagyszalanczy titled Woodshop Dust Control for all the advise you will need when choosing a dust collector.
All I can offer you here is an estimate of the size of dust collector you may need depending on the size of your shop and the machines you plan to operate. Most dust collector manufacturers will list the capacity of their machines so you can judge fairly well from this information if a unit is suitable or not.
Portable Units
These smaller dust collectors are ideal for the small shop that will only be operating one machine at a time. This is the general setup for the one person shop and the weekend woodworker. This type of unit can be moved from one machine to the next and is positioned close to the machine and is connected by a short hose. There is usually little effort or time needed for this setup and it is the cheapest way to get started with a dust collecting system.
Choosing a dust collector for this size unit, you would do well with the Jet DC650 that has a good reputation as a reliable dust collector and is very reasonably priced. It will move up to 650 CFM and this is generally enough for the small shop. It is compact and since available room is often an issue in a one man shop, this will do the job nicely.
More Power
Still in the portable class but able to handle more chips and dust would be either the Delta 50-760 or the Jet DC-1100 that both in the 1100 – 1200 CFM range.
These units may be portable but they will deliver enough power to clean up the chips and dust from almost any home wood shop machine.
Stationary Dust Collectors
The two machines mentioned above are capable of handling the job as a central dust collector for the smaller shop along with the Delta 50-850 or the Jet DC-1200. All rated between 1100 and 1200 CFM. With this system the dust collector and collection bags are kept in a central location away from the machine and a system of ducting is setup to each machine and controlled with gates to select the machine that is in use.
This is an ideal setup for the bigger shop and will mean that you do not have to move the machine around, a very good system if you have the space and finances to accommodate this type of setup.
Larger Units
If your shop is larger and you plan to run more than one machine at a time, or the machine will produce a lot of debris, then you may need to step up to a 3 horse power dust collector such as the Powermatic Model 75 that will move 1900 CFM or you may even need to go up to a 5 horse power machine like the Delta 50-765 that will move a very impressive 4700 CFM. The alternative to this larger unit is to set up with 2 of the smaller units working on only one or two machines.
The dust collecting systems on this page will help a great deal in keeping the wood shop clear of rubbish and will clean a lot of the wood dust from the air. Unfortunately there will still be a considerable amount of the very fine dust hanging in the air, and this is the most dangerous of all of the dust as it is what you will be breathing in all day, so the next step is to get rid of that danger as well.