|There's more than one way to do things|
If you install a 32-bit perl on your 64-bit OS, you'll notice almost no differences at all. But you won't gain a huge amount either. Most everything you have from your 32-bit OS will still work exactly the same, but you will still be restricted to 2 GB of memory per perl process.
Conversely, if you opt for a 64-bit perl, you'll find some things that won't work, but you'll gain access to all your physical ram per process.
There are two main sources of incompatibility:
My personal take on it definitely go for the 64-bit OS, and seek out 64-bit versions of as many of your favourite apps as you can find. You won't regret it. Remember that pretty much every 32-bit app available will run perfectly happily under 64-bit Windows.
Install a 64-bit perl as your main perl, but also install a 32-bit version as a fall-back for those hopefully rare occasions when you encounter a problem.
Setting your system up to make both available is relatively straight forward. I use the file associations mechanism:
If I name the Perl script .pl, then it gets run using the 64-bit install. Name it .pl8 and the 32-bit install runs it. Personally, I have rarely ever had to resort to using 32-bit in the ~1 1/2 years I've had a 64-bit OS, other than for the occasional comparison. (But I don't use OLE; life's too short.)
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"Science is about questioning the status quo. Questioning authority".
In the absence of evidence, opinion is indistinguishable from prejudice.