sony vaio vgn cr21s Windows vista SP2

make sure that you have SP2 installed

download Windows 7 upgrade advisor to check compatibility
http://www.microsoft.com/en-eg/download/details.aspx?id=20

Windows 7 requirements:
1 GHZ 32 or 64 bit CPU
1GB Ram (2GB is recommended) 32-bit
2GB Ram (4GB and higher is recommended) 64bit
15GB of free space on chosen partition

check the upgrade paths

Vista..........................................................7

Home Basic.........................Home Basic, Home Premium, Ultimate
Home Premium...................Home Premium, Ultimate
Enterprise...........................Enterprise
Business.............................Professional, Enterprise, Ultimate
Ultimate..............................Ultimate

(for example you can't upgrade from Vista Enterprise to 7 Ultimate, you will need to perform a clean installation if you wanted to)

you can't upgrade from 32-bit Windows to 64-bit or vice versa, you will need to perform a clean installation do change between 32 and 64


after running the upgrade advisor and checking that everything is compatible:

-perform a back up incase of something wrong happened
-insert Windows 7 installation disk then choose run when auto play message appears
-choose to download and install the latest updates to make the installation process smooth
-choose the "upgrade" method (I recommend you to perform a clean installation instead but it will delete everything on your C:)
-wait for it to finish

make sure that you have the right drivers from Sony
 
thank you for answering. the upgrade doesn't run it says it can't connect with my internet and here I am on line!!! What can I do? Also I do have the SP2 I am Vista family premium edition and the computer is a sony vaio vgn cr21s 32 bits with 2 GO
 
is it enabled through Windows Firewall?
these updates are not really critical but they help in making the upgrade process abit smoother, you can continue without them

I still recommend performing a clean install