Is there any reason why you wouldn't consider 64Bit. Your system appears to have enough umph to run it.
Newer software/games will be for 64Bit, but many are 32Bit compatible.
If I'm not mistaken, you will be capped at that 4GB RAM on a 32Bit Windows OS, whereas on 64GB you can go much higher. (If your motherboard supports more than 4GB RAM)
Coogan