Reformatting Computer. What to backup?

[hongus]

I run Windows 7 and I think I need to reformat soon because it's getting pretty slow. If I were to do this I have to backup wallet.dat, correct? Is there a way I can backup the whole blockchain so I don't have to redownload the whole thing? Also is there anything else I need to backup besides those two things?

[Pieter Wuille]

Yes, you can backup blk0001.dat and blkindex.dat from the same direcotry, and restore them there before running bitcoin again.

This should prevent you from needing to download the chain again.

Make sure Bitcoin is not running while making the backup.

[worldinacoin]

The wallet is the essential, the rest of the chain is more or less optional.  I will just backup the wallet.