Try to create a zip file thats larger than 4GB

Its not a marketingstrategy (not only tough^^)
Why on eath do people try and blame Microsoft for stuff outside its control. Much as they would like to alter them to suit themselves I'm sure Microsoft is still bound by the laws of physics like every one else.
The original addressing scheme of the Intel Pentium chip would only allow a maximum address space of 4GB - hence the OS was designed to work within this limit. Modern CPU's don't have the restriction but to use > 4GB in a 32 Bit OS requires quite a lot of complex "jiggery" at the OS level and a lot of re-write in the kernel -- and since around 99% of CPU's these days are 64 bit capable it doesn't make ANY sense in having different versions of a new 32 Bit OS. Windows 7 is likely to be the LAST Microsoft 32 Bit OS in any case.
For the more technically minded IBM in its earlier mainframe days had a similar problem with MVS 370 / MVS 390 OS'es. Their original CPU's could only handle a 16 Bit adressing scheme -- when the new CPU's came out which could handle more they still stuck to the base 16 bit addressing scheme but then had another 15 bits to address "Different Banks" of 16 bit memory. One Bit was reserved in the scheme to tell the CPU whether it was operating in "traditional 16 bit mode" or 31 bit mode. A lot of hardware was necessary to handle the switching and addressing in the early days to make the system perform acceptably. For the old timers who worked on IBM mainframes this stuff was handled by a special piece of protected fast storage located at a special address within the OS called the PSW (Program Status Word) -- refer to MVS/ESA for more details if you are interested.
If you've got 8GB either upgrade to X-64, run several Virtual Machines with the 32 bit OS concurrently or use the excess RAM > 4GB as a RAM Disk.
BTW as far as photoshop is concerned it knows at install time whether you are running on X64 or X32. If you upgrade to X64 bit OS'es re-install photoshop -- your key is still valid - but remember to
1) uninstall photoshop on the X-32 bit OS
2) TRANSFER ACTIVATION
3) install on your X-64 bit machine.
Other note on 64 bit Photoshop -- if you are using Camera RAW don't forget to add the RAW update (Camera Raw.8bi) to Program files==> common files==>adobe==>plugins==>CS4==>File Formats==>CS4 do this for BOTH the PROGRAM FILES directory (X-64) and the program files-X86 (the X32 version).
In the CS4 download package there should be two versions of this file in the install directory one under win64 directory and one ( X-32 bit version) under the root. If you can't find these then download (Free) from the adobe site under Camera RAW.
You only need this (these) files if you have a recent camera model - compact or DSLR and you do "RAW" processing. If you don't understand what I have written here don't worry as you won't be using RAW processing -- Pro shooters on the board will understand what I'm getting at here).
Cheers everyone and have a great weekend -- finally getting some time off.
jimbo