Problems downloading larger applications on a iPhone 3GS

Question

Ok, I will try my best to clearly explain what's happening. Before I even attempt to do that, I will let those who need to know. That I went through over 8 pages of many different posts trying to find a problem similar to mine, with not much luck. There is no way that I'm going to go through 1235 pages of posts here in order to find one that might answer or solve the problem. I also use the search option to try and find a similar issue like mine. That's not to say there was none though, I wasn't able to find one.
I'm running iTunes version 10 and Windows XP Pro updated to service pack 3.My system meets all other requirements that I could find available on Apples iPhone website. I'm also using the usb cable provided with the phone.
I've had my phone about a month now and I absolutely love it! The many diferent things that this phone will do is totally amazing! I repeatedly find myself thinking of the older Dick Tracy comic when I'm using this phone.
Now onto my problem that is some what sporadic until it comes to trying to install mostly larger applications or games onto the 3GS. When I say larger I'm talking about app's that are 250 mb or larger. The same holds true with the software update for the phone, although I'm not certain as to the exact size of the update. But when ever I try to install any program as I said larger than 250 mb I always get the same type of error and iTunes needs to shutdown or stop the install.
Windows tells me that there is a accompanying text to explain the error and where it's suppose to be saved at so I can read it. Upon going to the the temp file in the documents directory it isn't in the folder. Best I can tell it is listing the various program dll's that were needing to stop running. An most if not all of them were related to itunes.
I'm by far not a genuis in programming but I'm lead to beleive that this is more of a itunes issue and not windows. But hey, who am I to say so? Any ideas?

Answer 1

OK, reinstalled, turned off all firewalls, anti-virus, spyware, ad-ware, and anything else that didn't need to be running in the background. And it had the same results, no matter what I did. Even worse now, I thought I would try and download some smaller apps from my iPhone. Successfully downloaded each app without a hitch, but now when I use itunes on my PC. I'm told that itunes needs to copy those programs from my iPhone to the library on itunes. Does good until it gets to one of the larger programs, which to be honest isn't all that big "82 mb". I get the same error stated earlier.
So now, I'm pretty much screwed unless I just use my phone to download through my wi-fi, which performs flawlessly, other than what I just explained. Is there anyway to turn that feature off, then I can use itunes on my PC? I've downloaded some apps that are in the library in itunes, now I'm unable to transfer them to my iPhone.
Is this just related to the 3GS or is this being seen with the 4 also? Am I the only person who purchased a 3GS and is having the same problem? Anything I can supply or inform anyone with regarding this issue I will try my best to do so.