Upgrade from Exchange 2003 to Exchange 2010

Hi,

I have 2 DC at my network:
1: Winserver2008
2: Winserver2003 +Exchange server installed

I want to upgrade my infrastructure to have Exchange2010 ,
so I need to prepare /forest,domain and schema

I want to prepare these items some days before installing new exchange (2010)
Can I prepare them before installing Exchange server and install Exchange some days after?

Does it affect to my servers performance?

Thank you

It is possible to migrate from both Exchange 2003 and Exchange 2007 to Exchange 2010. As shown in the article Transitioning to Exchange 2010 that you can find in this link, you can see that Exchange 2003 is supported.

You can only transition to Exchange 2010 from the following existing messaging systems:
•Exchange 2007 messaging system
•Combined Exchange 2003 and Exchange 2007 messaging system