Onyx is a maintenance program for OSX. It's actually just an interface to run a few terminal commands, but if you do not know the terminal, then this is your best option. The program's main advantage is that it runs daily, weekly and monthly scripts automatically, which means that you no longer need to repair your disk permissions manually, delete cache files and all other cumbersome tasks.
Onyx can be downloaded from here.
If you Mac or OSX crashes, and yes this can actually happen, you may want to install your Mac using a Time Machine Backup. In order to do a system restore from Time Machine, you need the backup to be a full backup. If any of the system files are missing then the restore will fail. In general it's advised to install Snow Leopard from the DVD's and then use Time Machine to copy files back to your Mac. Time Machine usually includes your user folder and programs installed on the system.
The following procedure can also be used after installing a new hard drive in your Mac. Remember that you can replace the hard drive without burning your warranty!
There have been several expatriates getting into trouble with Apple Support after they had their iMac's and MacBooks upgraded by a non Apple Service Center.
They will also tell you that the installation has been damaged and/or cannot be upgraded and try to charge you for that. This is in no case legal. All the major computer manufacturers have been forced to either customers to upgrade their computers or install the hardware for free. This is also the case if the customer brings their own hardware. This is why all computer manufacturers now allow upgrades.
Recently I've had a few calls regarding the installation of Windows XP SP3 (Service Pack 3). In general it's always a good idea to upgrade your Windows installation with at least the major and important updates. Before attempting an install of Windows XP SP3 on a Mac though, you should create a backup of all your files.
I know that many of you use Mac's so I'll just start posting a few tips and tricks on how to use them. If you need more specific tips or help please feel free to contact me.