Modify your hard drive space.

Simply use this image. Click Start. Right click on Computer. Now select Manage. At left side under storage category click on Disk Management. Now select and modify your desired partition. Now you can delete, shrink or extend a hard drive partition.
You are done.

Enable administrator account.

Click on the start button. Then click on the all accessories. Now right click on Command Prompt and then select Run as administrator.

Type net user administrator /active:yes and then press enter.

And you are done.

Using two operating system in your PC.

Open command prompt or type cmd.exe in run. Then type this-
bcdedit /create (ntldr) /d "Windows XP" and press enter.

Then set the path where you have installed your windows xp. For example, D directory. Type following-
bcdedit /set {ntldr} device partition=D: and press enter.

Then type following-
bcdedit /set {ntldr} path \ntldr and press enter.

Now you should add this to boot up screen-
bcdedit /displayorder {ntldr} /addlast and press enter.

Now reboot your computer. Hope it is done.