I've been running Win 7 64 for two and a half years now and I've never had any reason to open the 32-bit Photoshop.
In fact, I just had to check my installed programs to be sure that I had indeed installed it. Yup, it's there, but never used.
I'm not using an SSD for boot, so I installed the 32-bit one anyway when I installed the 64-bit version.
In your situation I'd be tempted to keep a copy of the installation files in case you ever need them, but not on the SSD.