The same as in pretty much any other Linux or Unix distribution.
NOTE: If you wish to repair a file system, it is recommended that you dismount it first (umm, strongly recommended, in fact).
Switch user to root and issue the fsck command (dismounting the file system first if disk repairs are intended) passing the pathname of the device to be checked (and optionally repaired) with the fsck command.
Most implementations of fsck include command line interface switches that permit interactive repair or automatic repair of file systems, depending on the user's knowledge levels or personal preferences. If you aren't familiar with the particulars of file system repairs on the file system to be checked, it is recommended that fsck be allowed to make it's repairs automatically.
Lastly, if the file system was dismounted before fsck was run, remount file system on desired mount point and use as desired.
program would you run to check for possible disk errors
A windows based utility for finding and fixing physical and lofical errors on disk
Ubuntu uses the ext4 file journaling system, which doesn't get fragmented.
Yes, it can be done from the windows installation disk, but it's cleaner if you remove ubuntu with the ubuntu live cd and then install windows.
GNOME Disk Usage Analyzer
disk space analyzer
No. After download and burn the Ubuntu 10.10 install disk, you can either TRY Ubuntu without affecting your Windows at all, or INSTALL Ubuntu to have them both in your PC. However, to install Ubuntu, you need to be careful. Make sure not to install Ubuntu to the Windows drive. That is all.
When you first install Ubuntu, it will walk you through the steps to install it and keep your other OS installed. Then when you boot your dual-boot system, you can simply select Ubuntu.
try to scan your disk for errors
fsck /dev/(device) or fsck (mountpoint) to check one disk fsck -A to check all disks
just insert the disk open it right mouse click on the folder of the disk open with wine(you can get it in the ubuntu software centre) run the setup
Ubuntu is a free system program. Therefore, all of the software which comes from Ubuntu is free as well. One might want to check out from the main website of Ubuntu.