Justin,
The cabinet libraries are a great way to get started quickly in eCabinets but the best way is still to build your own library. Take the standard upper,base, tall and corner cabinets that are in the software, change all the construction to build the cabinets the way you want to create your own "Seed" cabinets (you have to give this a lot of thought to make sure everything is just the way you want it) then use those seed cabinets to build a library of every cabinet you might ever want to use. By building a library off your own seed cabinets with proper construction parameters you will have a library that also reflects your construction parameters. If you build your Library with all the correct parameters (this will probably require that you get familiar with the constraint manager so that you can make a cabinet retain some measurements) then everything will be correct when you re-size.
If you decide to download a library, the first thing you will want to do is to take each cabinet (around 225 in my libraries) into the cabinet editor and change the construction parameters to match your own. This is actually more time consuming than creating your own library from scratch and leaves more room for mistakes. The other option is to simply build cabinets the way the author of the downloaded library builds. This will get you started immediately.
Using any cabinet design software, the initial setup of the software is the most important thing you do. Don't skip steps to get up an running faster. These skipped steps will bite you later.
Give your software setup a lot of thought and take time to completely learn every part of the software you are going to need to use. Learning it now will minimize the problems you are going to have down the road.
eCabinets is a very precise software but you must enter all the information it needs to operate.
Kerry