Parallels files using up my hard disk - what can I delete?

I am running Parallels Desktop 3.0 (Build 5608) on a MacBook Pro running MacOS 10.5.8, with 4GB of RAM and 150 GB hard drive. I just received an error message telling me that I have almost no hard disk space remaining. Upon investigation I found that the Users/me/Documents/Parallels folder on my Mac contains files totally 51.5 GB (this despite the fact that I have almost no files stored in the Windows installation that I am running under Parallels).

My question is: can I safely delete some of the files or folders that are in the Users/me/Documents/Parallels folder?

This folder contains two subfolders:
1. Users/me/Documents/Parallels/Microsoft Windows XP 4
2. Users/me/Documents/Parallels/old parellels [and yes, the folder "old parellels" is spelled that way]

The "old parellels" folder contains a total of 32 GB of files in 5 sub-directories (none were modified more recently than summer 2008):
1. Microsoft Windows XP
2. Microsoft Windows XP 1
3. Microsoft Windows XP 2
4. Microsoft Windows XP 3
5. winxp

I don't know where this folder and the subfolders came from but I'm guessing that they were created by one of the ITS people at my job.

In any case, can I safely delete the "old parellels" folder without affecting my Parallels installation or the files that I have stored within Windows (under Parallels)?

Aside from the "old parellels" folder, the other folder in users/me/documents/Parallels/ is a folder titled "Microsoft Windows XP 4". This folder totals 19.4 GB and contains:
Microsoft Windows XP.pvs (last modified today)
Windows Applications folder
Windows Disks folder
winxp.hdd [this file is 19.4 GB and presumably it contains my Windows installation and all files and folders in it?]

Many thanks for any suggestions,
Abe Z.