Be sure to wipe your HD to get the cleanest possible slate for Windows 7 clean install. SSD / HDD : Optimize for Windows Reinstallation
If you buy a Windows 7 Upgrade version it will require using one of the workarounds given here to install Upgrade version to formatted HD: : Clean Install with a Upgrade Windows 7 Version
Back up your files first and gather your program installers. If you need Product Keys for software, audit the software/hardware using Belarc Advisor.
Windows 7 installer is mostly driver-complete, with newer drivers arriving quickly via optional Windows Updates. Any drivers then missing can be found on Support Downloads webpage for your model device.
Install programs slowly to gauge performance after each. Don't let any programs write themselves into your msconfig>Startup list besides AV and gadgets - all others are freeloaders on your RAM/CPU.
When done, clean and order the HD perfectly with state-of-the-art free CCleaner ("Run Cleaner" and Registry tab) then Auslogics Disk and Registry defraggers.
When it is set up perfectly, save externally a Windows 7 Backup Image so you never have to reinstall again, just reimage your HD or a replacement using the DVD Repair console or Repair CD.