Well, If it comes down to a simple Homenetwork - and a PC crash, normal situation is following: You're mostly dead in the water.
Why?
Because most ppl don't backup their data on a regular basis or do it wrong.
Actually, there are 3 kinds of pepole:
a) The person who doesn't backup
b) The person who *thinks* does a backup - but does it wrong
c) The person who does a backup and stops after a while because he is too lazy... and experiences a crash...
Well, I myself count am Type c) - I did backup for example my E-Mails in Outlook Express - but stopped after a while, and a year later I got a really big crash.
So, today, I use Thunderbird ( đ Thats plus, ain't it? ) and I do backup at least weekly - or on an "ohmygodthatcouldturnoutbadithinkishoulddoanbackupNOW!" basis.
And because I got three computers already in my network which does need backup and updates on an daily basis, I built myself an little nice Dual Atom based Server.
But thats another story.
So, here the best tools for backing up your data and my personal notices to that, have fun and take care!
Databackup:
Rsync
Rsync is the most widely used backup tool in the unix world. And it does also come in an windows flavor!
The best thing about rsync? It does only transfer file changes, and not a stupid "folder-to-folder" copy.
Rsync is a client-server based tool. So the best idea is to install the server on an "real" server with some nice RAID5 System,
and let the client do the work on for example your windows xp machine. Oh, by the way: There is no problem in having
an unix/linux rsync server and an windows xp client. Works out all the way. But thats not the only thing you can do:
You can also install the server and client on the same pc and use it to make backups from your usb stick to your harddrive (for example).
Rsync: http://samba.anu.edu.au/rsync/
DeltaCopy (Windows Rsync with Gui): http://www.aboutmyip.com/AboutMyXApp/DeltaCopy.jsp
FTP / Webbackup:
FtpSync
If you're the poor kind of person which does host its Website with an "you-get-no-shell" hoster like I am, you need to backup your Website in another fashion as rsync:
FTPSync seems to be the perfect solution because it only transfers changed files, it does reduces the amount of "for backup used bandwith" by a big deal. (I myself host about 600 mb now on files, pictures and other things - and this little guy is really an helper) FTPSync does run on Windows 2000 and above. It can use scripts / ini Files which allow FTP-To-FTP Sync, as well as FTP-To-File Sync. So, also useful if you build up your Website on your Homeserver and want to commit the changes.
FtpSync: http://www.cyberkiko.com/category/FTPSync.aspx
Mysql Backup:
Mysqldumper and phpMyBackupPro
As already mentioned, no shell access is a hard thing for an Website Administrator. Especially when it comes to Mysql Backups - called Dumps. Well, yes you can use phpMyAdmin to Dump these Files - but there is a maximum php execution time which does sometimes corrupts your backup - in case the database has grown too big.
In this case there are two tools which will help you: Mysqldumper and phpMyBackupPro. First: They both do backup and restore. That said, what are the main differences? a) Mysqldumper has the advatage of using multiple mysql logins, as given away by most hosters (you get for example 3 databases, and everyone got another login name and password - its more secure and you can use it and share it with other projects). b) phpMyBackupPro is easier to configure in terms of cronjobs, so automatic backups as Mysqldumper. Which of these tools you use is your choice, and depends on the features you need.
Mysqldumper: http://www.mysqldumper.de/
phpMyBackupPro: http://www.phpmybackuppro.net/
Tipp: You should use the Mysql Backup Tools in conjunction with FTPSync to Backup your complete account.