You should NOT be using a 64 bit OS with 1GB of ram. Why would you do that? A 64 bit OS is inherently more RAM hungry and slower when RAM constrained than a 32-bit OS. Not to mention that the 32 bit version of Windows 7 is SLIGHTLY more compatible with old Win 32 games (such as Civ 2 and Fallout 3).
The whole world is moving to 64-bit OSes, but not just for the fun of it, the only reason for the move is Virtual Memory Address Space (more than 4GB of it) .. you wont see ANY benefit to a 64-bit OS until you have more than 2 GB of RAM, or more than 3 GB total of RAM + Video Memory. All of my computers have finally moved to 64-bit OSes, but that's cause they have between 4 GB and 16 GB of RAM (and 1-2 GB video cards). I promise you will see 5-10% faster performance on a 32 bit OS, and have about 50-200 MB more free memory from Windows 7.
As for free C++ IDE, I've used Visual C++ Express 2008 and 2010 (which were required by the older XNA SDKs) and like them just fine. I haven't used VS 2012 express yet, partially because there is no longer an XNA for it, and I'm not currently doing any open source / indie work so I'm just using the professional version. And partially because of this: http://www.lifehacker.com.au/2013/01/ive-given-up-on-visual-studio-express-2012-for-windows-desktop-heres-why/. Although I have to say that VS 2012 is better than 2010 in some simple ways, I just can't believe they removed the exception diag feature - way to help the beginners.
Code Blocks has been highly recommended for years as well, and in the game dev beginner community I pretty only see those 2 (Visual Studio Express and Code Blocks) used with enough users to be helpful.
If you use VS Express be aware of a few things. 1. you CAN make multi-project solutions, you just have to tell it to ADD a project to an existing open solution ... and it will then be visible (the solution is hidden by default). 2. you CAN make it remember tabs instead of spaces, you just have to use REGEDIT to change the settings, since they removed this setting (and most) from the Options dialog.