How to return iPhone software to previous version after upgrade

I have not had to retore my iPhone yet, but did you try using the Restore feature in iTunes. Theoretically the last backup in iTunes was for the previous version. Maybe a Restore will do it.

I found this Article Here

I know you have Windows 7, but maybe the location of the files will help you somehow.

Restoring old versions of your Backup

Restoring backups of your iPhone takes just a few clicks, but iTunes often only shows your most recent backup as an option to restore from. If you ever want to restore your Older backups then you’ll need the assistance of Time Machine and Time Capsule.

If you’re not already backing up your system, you may want to utilize this incredible thin mini external hard drive. It has enough space to backup significant amounts of data and will work great in backing up your iPhone.

iTunes stores your backup files in a folder at this location: /Users/[username]/Library/Application Support/MobileSynce/Backup. In this folder will be an additional folder or two. These folders contain all the data on your iPhone settings.

If you want to restore your iPhone to a backup you created 3 months ago, navigate to the location listed above, select the folder and open Time Machine. Navigate back 3 months and then click restore.

After Time Machine has finished restoring your Backup Folder, follow the steps listed above to Restore your iPhone Backup.

While Time Machine is a great feature in OS X Leopard and above, I’ve personally had two external hard drives fail while being used for backups. Luckily, I had previously backed up onlinemy data to keep things safe. Online Backup works great for restoring data, like your iPhone Backups and allows you to have extra piece of mind while keeping your data safe. Best of all, with companies like Mozy, online backup is cheap. I’ve used it to restore data and its quick, easy, and the software on the PC and Mac runs in the background without getting in the way. Check it out, back up your data, and be ready for the next time you need to restore your iPhone backups, even if Time Machine isn’t.

Even if you restore from a backup your software version will not change.

Before you try to roll back, which is not supported, try some other steps first:

As to the "slowness" which you don't describe, Reset your iPhone, i.e., hold down the sleep and home buttons, ignore the red Off slider, wait for the Apple logo, let go of the buttons.

On to the apps: using your iPhone download one free app from the app store then run it. Now try your other apps.

wanted to know if I can recover my previous version .I just switched to ios5 and lost contacts,memo app,itunes music on iphone.I hope so.I use win-xp on a netbook.help!