Hello serhatyonder, Link Removed to Windows 7 Forums,
Slipstreaming SP1 in to a Windows 7 ISO is not a bad idea, I've done a few myself with SP2 & 3 in Windows XP Pro, however, slipstreaming updates in to an ISO IMHO is not such a good idea, especially with Windows 7, due to the fact that is only a few years old and continued support through 2024, I believe, you will be facing undoubtedly another SP and many, many more updates, so, you would be continuously updating the ISO and I honestly think, you do not want to go through that.
The best thing for you to do is to make a separate DVD for SP1, then when the next one rolls out, make one for that.
This way anytime you re-install Windows 7, once rebooted and running fine, install...