My guess is that it ran out of hdd space, but the file is only 30kb. my backup is 120kb, but i suspect its out of date, i was only doing weekly backups. it doesnt load anything on my 3 machines when i try to use it.
Congrats: You're probably less screwed than you think.
When you load it on another machine, do a rescan, then wait a while while the machine thrashes and rescans the block chains up to the current network position. When you load a wallet on a machine with a more recent blockchain, you usually need to trigger a rescan to make it find transactions.
"doesn't load anything" is unlikely even with a somewhat out of date backup, instead an out of date backup will usually show some of your balance but not all of it and If you were not doing more than 100 getaddresses sends per week then your backup should not be out of date.
If this doesn't fix you, then it still might be possible to recover your coins from the db log files in the bitcoin directory on the machine that broke. Make a backup of the whole bitcoin directory block chain and all just in case.
Even if we're not able to help you get your coin back we should still dig in a bit to the specifics of your loss like why didn't your backups work, so that better advice can be given in the future. After all, you were backing up, and for many users weekly is more than enough.
