Check your BIOS, is it set to AHCI or RAID now?
AHCI and RAID settings in the BIOS are the same functionality. The only difference is you can't run a RAID array in AHCI mode, everything else is the same. This means if your BIOS is currently set to RAID you don't need to change anything, and you don't have to run any disks in a RAID array.
The only reason to change settings is if your BIOS is set to 'IDE', then you need to follow the steps below.
1) When you do a Clean Install of Windows 7, connect only the SSD, do not connect the old HDD. This will insure the boot files get on the SSD where they should be. If you have the old HDD, it will likely be marked 'Active' and the new installation will put the boot files there, if you ever need to remove or change the old HDD your system will not boot.
2) Change your BIOS setting to AHCI or RAID just before you do the Clean Install of Windows 7 (as you have mentioned), then the new installation of Windows 7 will be in AHCI/RAID and you won't have to do anything else.
3 & 4) Ok
5) No need to do this, the Windows 7 install will load the msachi drivers, you can load the Intel RST drivers from within normal Windows 7.
6) Install Intel RST 184.108.40.2066 and restart.
Install the Intel RST driver: Intel® Rapid Storage Technology Version: 220.127.116.116
Don't install any versions newer than this one, they are known to cause instability for many users.
I have confirmed this on my own Dell systems.
There is no need to install any other Dell RAID drivers, the Intel RST driver is all you need.
The Reg Edit is for changing from IDE to AHCI/RAID if your installation was done in IDE mode, so if you follow the steps above you will not need to do anything in the registry.