In practice 32 bit will only access approx. 3.4GB.
That said, if all you are using the PC for is office type work (e.g. word processing, spreadsheets), web browsing, viewing photos / videos (not video editing), you probably won't even use all of the 3.4GB.
Windows updates are much smaller. I had W7x64 on one machine and W7x32 on another. The updates on x32 were about half the size.
Also the disk usage by the OS will, accordingly, be much less. Arguably, it follows that x32 might be marginally faster (as there is less to transfer around).
Old software is more likely to work with x32. I have some old Win3.1 software - works under W7x32, but not W7x64 (won't even install in any way shape or form).
Also x32 supports 32 bit drivers (you absolutely cannot install 32 bit drivers on an x64 OS). So if you have old hardware with only 32 bit drivers (e.g. scanner, printer) the drivers may well work under x32.
Security on W7x32 is said to be marginally less than W7x64 (don't know if same holds true for W8).