My iPhone has been with me for years, bought it from my brother at a lesser price, i bullied him the reason he lowered the price lol! The applications was customized by my brother and just a few days ago I decided to make some changes. I hated iTunes for some reason, one of which is that most nice apps are all price tagged. Another thing, since I'm a second owner of the phone I deactivated my brother's iTunes account and made my own but 'twas a bit of a problem. At first attempt my new account didn't go through then tried it a couple of times and still 'can't access. After several months, I can now access iTunes -weird!
For an easy know-how, there are actually two ways to have new applications on your iPhone
1. Via phone
You can actually use the default application on your iPhone "App Store", this is powered by iTunes. It is where you can look for free downloads. Try clicking one free item, it'll load directly onto your phone. I've been using this since forever because I don't like the idea of downloading iTunes on my PC but that was before.
2. Via PC
iTunes 10.6.3 is actually for Windows XP, Vista or Windows 7
Also, check your PC's compatibility with version 10.6.3
I find this better than downloading apps from my iphone, You can transfer your choice apps all at the same time with no downtime and it's easier to browse.
Now here's How to transfer applications from Itunes to Iphone without crashing the phone
Here's my story, I downloaded Itunes on my PC, stored it on Drive C. I connected my phone and this popped on my screen
I readily clicked Update, and that's when my problem started. My phone has gone haywire, all my current applications became inaccessible -when you click the apps, it simply opens then gone in a second. I searched for possible answer to no avail and seen quite a number of people who were in my shoes and are already annoyed.
I figured it out, my mistake was I didn't check my free space on Drive C (Drive C space is running low), It's very important to check before proceeding because when you update to a newer software version, everything on your phone will be wiped out not unless you made a backup on your PC.
Once you're done updating, make sure on the "Device", it reads User's Iphone/Iphone, that means your phone is properly connected to iTunes.
Then click "Apps", At the Lower right you'll see "Get More Apps", click it. From there you'll be able to see all categories. Pick your choice then click Download, then right click on "Iphone" under "Device" and click "SYNC". Once the download is done, click "Transfer Purchases", you can now check your phone for new applications.
I hope this helps. Much ♥