I am using both spacers, and what are called "adaptors".
Spacers are simple plates of steel with holes. Adaptors have studs pressed in. Typically, spacers are not recommended once going larger than 0.75 or 1 inch. Beyond that, you should use adaptors.
You can also buy spacers and adaptors that are "hubcentric", which means they have a small lip that sticks out like your hub does.
When using large spacers or adaptors (anything larger than 0.5") I strongly recommend upgrading to better studs. ARP is a well known brand for good studs.
When using adaptors, I strongly recommend either Steel or Aluminum Billet. Avoid anything that is cast, and only buy adaptors that are machined from a block of metal, with "pressed in" and "knurled" studs. It's another bonus, if the studs were pressed in, and heat treated to harden and cure in the adaptor.
TransDapt sells cheap 1" adaptors on summit. AVOID these! They are cast aluminum and very prone to "shattering"... very very dangerous.
Basically any adaptor or spacer is good if it fits this criteria. If your car is not ment for hard driving, you should be fine with stock studs. If you are using large spacers, you will need to get extended studs. A spacer will run you anywhere from $5 to $20 depending how thick you go. An adaptor is typically $50 to $80 each... if there is a machine shop near you, it may be worth it to get some made.
hope that helps...