Please be advised that Dell has not tested this system for Win 7 OS functionality and hence, there are no Win 7 drivers available for install.
If the system is slow, then kindly check if the HDD is functional - Restart the system and press f12 key on startup - choose diagnostics. Let it run the diags and if you encounter any errors - make a note of the complete error and report the same to us. These are onboard diagnostics and they might possible pick some error if the hardware is not functional. Also, run an extended / thorough tests on the HDD and memory to check for any possible errors.
You could find all the archived drivers listed here.
Also, please click my DELL-username and write me a private message with the service tag and your Name for case records.
Let us know if you have any other queries.