Speed up Exchange 2003 Performance

Anyone out there who could recommend the best way for Exchange 2003 to perform much faster and easily restore a calendar post or a mail being used by the user? Currently, our Exchange 2003, which is utilizing ntbackup for fullbackup, has about a hundred users and 50 GB of data. I’m not yet satisfied with its performance and I think it still needs an improvement. I’m thinking using Exmerge or 3rd-part application in order to achieve our desired performance, but I don’t know which one is better.
