I am using Windows XP SP3.
H:\Bitcoin>dir
Volume in drive Q is BITCOIN
Volume Serial Number is XXXX-XXXX
Directory of Q:\Bitcoin
2013-02-21 09:31 AM
.
2013-02-21 09:31 AM ..
2012-09-18 10:19 AM 0 .lock
2012-09-18 13:57 PM 3,850,240 addr.dat
2012-09-27 12:05 PM 131,072 backup.dat
2012-09-18 13:25 PM 2,097,384,811 blk0001.dat
2013-01-04 10:34 AM 2,097,346,788 blk0002.dat
2013-02-20 22:13 PM 1,561,011,203 blk0003.dat
2013-02-20 22:18 PM 1,809,104,896 blkindex.dat
2013-02-20 22:28 PM blocks
2013-02-21 09:22 AM chainstate
2013-02-20 22:18 PM database
2012-09-24 08:41 AM 0 db.log
2013-02-21 08:31 AM 564,356 debug.log
2013-02-21 09:31 AM 956,384 peers.dat
2013-02-21 09:18 AM 172,032 wallet.dat
What can I safely delete? I highlighted in bold and color what I think can be deleted. Can someone confirm this?
You can safely delete those that you highlighted. As the new files is in the "blocks" directory.
Easiest way for you to check is to close the bitcoin client, move those files to another directory and then start the client again and check if it starts downloading the blockchain again.