Wallet.dat can contain only 100 private keys even if I back up? Considering the Bitcoin client for Windows 0.8.1:

So the best way (if I have already used up 100 keys) is to send bitcoins to different wallet and then to newly generated one?

When I want new keys, can I just delete old wallet from default location and WILL BE THE NEW ONE GENERATED AUTOMATICALY when turning on the client?
Run the client with the parameter -keypool=10000 to generate 10000 keys in your keypool.

Pros: Less backing up

Cons: Your wallet will be bigger (file size) and take maybe a few seconds extra to load