Ok this topic has been blogged about alot. But I thought I would give my two cents.
So you have XP or Vista and want to do a clean install to get to Windows 7 Premium or Home Premium 32/64 bit, but have a upgrade copy or want a cheap upgrade well I will cover how.
The method I used and is the easiest and quickest is the straight install method with rearm (explained later).
Note: DO NOT INPUT THE UPGRADE KEY ON INSTALL.
So step by step guide.
Backup your data on your current machine, (You will need to reinstall all apps after installing Win 7).
Boot into the DVD/Flash drive, start your machine with the bootable media, Follow the install steps do a “Custom Install” and select the hard drive you want to install on. when asked do NOT put your upgrade key in here during the install.
When windows finishes installing and boots into windows, run the automatic updater untill there are no updates left.
UPDATE: Avoid updating to Service Pack 1 if the update is offered to you!
First we can just try using the upgrade key as a regular version key. Type “activate” into the start menu, enter your upgrade key and see if it activates.
If it works, great job done no need to go any further enjoy your copy of Windows 7.
If not… Then Me and a Matt Hayden worked on a little batch script that will do the work for you.
Download the Re Arm Batch File and unzip it to somewhere accessible.
Run the rearm.bat, it will prompt for permission to run, say yes, restart.
Type “activate” into the start bar again, re run activation and voila!
Any feedback on success rate would be great. I have used the second method personaly and worked no problems, although peoples mileage may vary.
Hope this helps.