I have 2 operating systems on my PC, how do I change the config to boot from the OS on the C:?

Some time ago, I turned on my computer, and something came up saying couldn't start windows, missing file. So I used the recovery disc on my D drive, and then copied that file to my C. Problem now is when it starts, I have to choose which OS to start. So how can I get it to automatticaly start C, and then delete the OS on the D?I have 2 operating systems on my PC, how do I change the config to boot from the OS on the C:?
Easy task...just go to run, type msconfig, then ok. Under System Configuration Utility, under the tab BOOT.INI, there is a small window under which commands that execute at system boot are written. At the last line of these commands is your operating system command (something like multi(0)disk(0)rdisk(0)partition(1)\WIND?Windows XP Professional%26quot;.....). You must have two of commands like this because you have two operating systems installed. So click on the operating system you want to load at startup and choose SET AS DEFAULT key given below.I have 2 operating systems on my PC, how do I change the config to boot from the OS on the C:?
Right click on My Computer, select Properties, click on Advanced tab, select Settings uner Startup and Recovery, click on the arrow and select the OS you want to boot automatically.