There are many different ways that you could do this. Some of the factors to consider are -
1. Are you confident enough to remove and reinstall a hard drive?
2. Will you have access to both PCs at the same time?
3. How much data do you need to transfer?
4. By data, do you mean the documents that you have produced and /or saved (e.g. Word documents, spreadsheets, MP3s etc), or the programs (such as Microsoft Office) as well?
5. Can you network the 2 PCs?
If you can answer the above, we can help narrow down the many choics available.