All of my cards claim to be 100mw wifi cards, so, would it be better to buy a Bigger Antenna (for extra coverage/range) or would it be better to buy an amplifier/booster?... what are the pro/cons of either?...

Any advice would be appreciated...

 

It depends what you are trying to do.

If you are just trying to improve coverage in a house, a second access point may be the best option. Link it via (wired) ethernet to your existing router, set the same network name but on a different channels (well apart).

Any portable devices will see both and automatically 'roam' between them depending which is strongest at any point.

If there is more than one person using wifi, this can also improve connection speed as you are making more bandwidth available when the load is shared over APs.

Virtually all WiFi devices have at least two antennas, even if they are not visible - some routers may only have one connector but have two or more internally.

This is important as UHF signals reflect easily and can either add or cancel as the path between the ends of the link changes. Both ends will use whichever antenna gives the best result (Diversity reception). The new 802.11n devices use three antennas and can transmit seperate data over each each to give better speed when the signal path is good enough.

For good results, you need to use external antennas to replace both/all three antennas on the access point. You would need these with or without the amplifiers, and you would need as many amps as antennas.

Also, antennas achieve gain by being directional - think of them like a lamp and adding reflectors or lenses; the source power is still the same, but it's more concentrated on one direction. This is great for long links, but not good trying to cover an area from a point source like a router.

The cheapest option is probably another access point - I use three to cover my house, spread about the loft. Linksys WAP54G units are cheap and readily available on ebay, but there are many others.