Before shrinking C I would uninstall any programs you don't use, clean up and organize your files into User folders which you can just drag to the new data partition. Confirm twice that all of your data is there.
Make your backup media if you haven't already as suggested in
Clean Reinstall - Factory OEM Windows 7
Then run
CCleaner Disk and Registry cleaners, followed by Puran Boot Time defrag with full Disk Check.
Puran Defrag Download before shrinking C in Disk Mgmt:
Partition or Volume - Shrink and creating a new which you label Data:
Partition or Volume - Create New
If you have not yet tested if the OEM diagnostics partition will boot I'd do that next to know whether to save the OEM partition:
Dell Diagnostics Utility - How to Run the
Reboot into BIOS setup, Set SATA controller to AHCI.
Then I would boot into installer using Dell F12 key at boot, during booted Custom install following the illustrated steps in
Clean Install Windows 7 . During Steps 7 and 8 highlight to Delete the Recovery (which will not run after reinstall) and C partitions only. Keep telling yourself you will not touch the Data partition to avoid a mistake. Then highlight the Unallocated space you have made from Recovery and C . Create and Format a New partition there only, click Next to begin install.
Be sure to have your wireless driver on a CD, stick or stored on the data partition downloaded from the Dell Support Downloads webpage for your tag number so if its not provided during install you can install it to get online, enable
Automatically deliver drivers via Windows Update (Step 3) then run all rounds of Important and Optional Windows Updates. After each requested reboot go back to Check for more Updates until there are no more. You can be setting up your desktop and browser while these are running, maybe installing some programs though I would spread those out to see if any affect performance.
If you prefer you can leave IRST enabled for this install to see if it is the cause of the BSOD's and retail the SSD chip paging cache. The reinstall may resolve the issue, but if not then you'll know to disable IRST to reinstall again.