Hi,
go to this link
www.cisco.com/go/fn
1- search by image
2- Software (select IOS )
3- Platform ( Select your router type)
Then continue to next screen
1- Select Major Release IOS version
2- Release ( Select ALL releases )
3- Select feature set ( SP services )
it will post IOS version, RAM and FLASH required for SP services on your platforms.
HTH
Jorge
Jorge Rodriguez