Guys!
Most of us face Lower Disk Space problem many times. Windows notifies us about the lower disk space and we are forced to delete some useless files or to resize the partition to get some free space.
I'm posting this tutorial to tell some methods to get as mush FREE space as we can. But use it at your own risk. I'll not be responsible for any kind of damage/problem in your system. I hv been using these tips since many years and never faced any problem. 
Following are some ways to get lots of free space:
1.) First thing is to use windows built-in "Disk Cleanup" application. You can right-click on a drive in My Computer and select "Properties" now click on "Disk Cleanup" button. Now select all given options, like "Downloaded Program Files", "Temporary Internet Files", "Compress old files", etc. Believe me you can get more than 1GB FREE space after using Disk Cleanup coz once I got approx. 1.5GB more FREE space after running Disk Cleanup. Alternatively you can run "Disk Cleanup" directly from RUN dialog box by giving "cleanmgr.exe" command.
2.) Now open Windows Search and copy paste following code in Search box and perform a search:
Code:
mscreate.dir;whatsnew.*;*.tmp;*.log;*log.txt;*readme.txt;file_id.diz;tips.txt;*.bak;*.old;*.syd;*.prv;*.grp;*.gid;*.fts;*.cnt;*.~mp
All above mentioned files are useless and you'll get 100s of files after searching, simply select all and press <SHIFT> + <Del>.
PS: Pls check the files before deletion! It'll delete all Readme files, Backup files, Log files, etc. So deselect the files first, which u don't want to delete.
3.) You can also disable WFP (Windows File Protection) service using WFP Patcher. This service runs in background and checks for system files' status, and whenever it finds a system file has been changed/modified, it replaces the file with the original file stored in "DLLcache" folder. So we can disable this service and can get lots of FREE space.
After disabling the service, open "%windir%\System32\DLLCache" folder (it'll be HIDDEN & System Folder, so copy paste the path in address bar and press <ENTER>). Now you can safely delete all files present in this folder. It'll make aprrox. 1GB FREE space. I always disable this service coz it always irritates me while hacking system files in my lovely Resource Hacker. 
4.) Open "System Properties" by right-click on "My Computer" icon on Desktop and select "Properties", now goto "System Restore" tab and select "Turn Off System Restore on all drives" option and apply it. Don’t use this trick if u use System Restore.
5.) You can delete several BMP files in %windir% (Windows) folder, which r used as wallpapers in Desktop Properties. You can also delete all files in %windir%\Web\Wallpaper folder, all files in this folder are also used as wallpapers.
6.) You can also empty TEMP (just type "TEMP" in RUN dialog box), Prefetch (in [b]%windir% folder) folders to get free space.
7.) Disable Hibernation from "Power Settings" (powercfg.cpl), if u don't use this feature.
8.) Empty Temporary Internet files of ur browser to get some free space.
9.) You can also delete all video files present in %windir%\system32\oobe\images folder, these files are used when windows runs for the first time after installation.
10.) You can also delete all Updates Uninstall Folders, which can be found in %windir% folder and all these folders' names will start from $NtUninstall (or something like that, can't remember the exact name coz I hv deleted all of them 
). But keep in mind that after deleting these folders u'll not be able to uninstall any windows update!
You can apply all above mention methods to get lots of FREE space without any problem, all these methods hv been checked by me many times and I always use them after a fresh installation of my windows.
You can also use 3rd party Utilities, like Tuneup Utility, System Mechanic, etc to FREE some space but these utilities also use most of the above mentioned techniques like 1.), 2.), 6.), 8.).
I hope u guys will like it.......