Solved Problem with Hard Drive Performance & Windows 7
Shortly after Win 7 RCP was released I installed the 32 bit version on a Dell Dimension 9100 that was configured with the following:
Intel® Pentium® 4 CPU 3.00GHz, 1 Core, 2 Logical Processors
4.0 Gb RAM
Intel 82801G (ICH7 Family) PCI Root Controller
RADEON X600 Series Video Card
This system previously had Windows XP Pro installed prior to the release of Win 7 Beta. For this install I chose Custom and reformatted the Hard Drive.
Shortly after installation i noticed a significant degradation in system performance. The hard drive was spending vast amounts of time writing/reading causing the system to hang. I had installed Win 7 RC 64bit on a Dell Inspiron laptop that exhibited no such problems and was performing great. I searched through the forums to attempt to find a solution. Running the Win 7 Troubleshooter produced no results and all drivers reported they were working normally. I kept digging…
Finding no solutions and little success in actually locating the culprit using the Event Viewer, I decided to perform a clean install of Win 7 64bit on the machine. After booting from the DVD drive and a successful install I was hoping that my problems were solved. Initially it appeared so, but soon after beginning the installation of additional software the system hangs returned. This time I was able to capture the Error in the Event log.
Upon diving a little deeper into the error the system reported the following detailed error results for ESENT.
I had never heard of ESENT, but the system was reporting faulty hardware. A quick Bing Search revealed that ESENT was the Extensible Storage Engine. I was able to find a thread on TechNet at http://social.technet.microsoft.com/Forums/en-US/itprovistaie/thread/bb335f62-4bc7-4853-ba93-1e4bfca74888 where the user was experiencing similar problems, but had attributed the problem to Internet Explorer hangs. The solutions offered in the thread did not remedy the problem, but were a good start.
The solution recommended involved 3 steps.
a) Click the Start button, and click All programs, then click Accessories.
b) Right click Command Prompt, and click Run as administrator.
c) Type sfc /scannow, and press ‘Enter’.
This will scan all protected system files and replace incorrect versions with correct Microsoft versions. After performing these steps, my system continued to experience the same issue. It was clear at this point that the hard drive or disk controller was involved so I began a hard-drive self-test and disk check of the drive. Surprisingly, no errors reported there either.
I wanted to take a closer look at the drivers for the Storage Controller so I opened the Device Manager, viewed the driver details and found that the driver provided for the Intel 82801G ATA Storage Controller was provided by Microsoft as part of the Win7 RCP.
I surfed to the Intel website and searched for my Storage Controller. To my pleasant surprise Intel released a new version of the Storage Controller software on 7/17/2009. The release notes indicated that my issue was one that was solved with this latest release. After downloading, installing and several reboots, my problem is fixed. No more hard drive whirring away for minutes on end doing nothing.
This may not solve the problem for everyone who experiences this issue, but it worked for me. The system this applies to is listed below so if this issue is your issue, try this fix.
For further detail:
Jay D's Blog 
Just an update to the situation described above… I obtained my Win 7 RTM version and installed today. The same issue appeared again. I installed the Intel update/driver and the problem is resolved yet again.
I had had the very similar problem with my Thinkpad X100e w/ AMD CPU/chipset for a long time. After reading your blog, I tried to install AMD’s storage driver instead of MS’s standard driver, and then, my X100e finally started running smoothly without any suspension. Thank you very much, Jay.