Are you sure you actually removed the entire Windows folder or just the reference to it in the loader?
Have you tried booting into safe mode by tapping F8 on start up?
I am not familiar with the Acronis loader so I don't know how to fix it.
What is the other OS? The following MAY work. As I stated I don't know about the Acronis loader so I don't know what got deleted.
Do you have a full version WinXP CD? If so, boot to it and use the recovery console. Use the commands Fixboot and then fixmbr.