ATMEGA2560 installing on Windows XP

Hello,

I used sinced beginning of this year an ATMEGA2560 (IDE rev. 1.05) board on my Windows 7 Laptop, without any problem.

I tried to install it on another older Laptop, with Windows XP SP3. The version of IDE is 1.05-r2

Downloading of application is not possible because of serial link problems.

My question is :

Is Revision 1.05-r2 OK to be installed on XP, or do I have to download an older version ?
Is there a difference using the "Windows installer" package instead of "Windows zip file (for non-administrator install)" ?
=> I used the second one because I lost my administrator password on this laptop ...

Thanks a lot for your help.
Emmanuel