Please post back a screenshot of your maximized Disk Management drive map with listings showing all columns, using Snipping Tool in Start Menu, so we can advise you better.
All Windows 7 installers are the same - it's the key which determines which version will activate. Also either 32- or 64-bit can be used with each license. So if you want to keep 32 bit you could activate now at Computer>Properties with Product Key on COA sticker as long as it's same version.
But you obviously want to use your full RAM so it's too bad you didn't run Asus Factory REcovery instead of clean reinstall as now your Factory Recovery options may be limited to ordering Recov Disks from Asus Tech Support if you didn't make them earlier.
However you can locate any 64 bit Windows 7 retail installer to Clean Reinstall again with the Product Key on COA sticker. If you download from web, be sure to get a safe copy by googling Official Windows 7 ISO Download at My Digital Life, then burn to DVD or write to flash stick using this tool: Windows 7 USB-DVD Download Tool
Here are tips to getting a perfect clean reinstall of Factory OEM: Reinstalling Windows 7
. It is our specialty here so feel free to ask any questions as we are here to help you get and keep it perfect.