If you do you will need to get hardware that has 64 bit drivers. I updated to 64 bits back when Vista came out. I had to get a new audio interface.
 
There are advantages in going 64 bits. If you read this thread its likely they have been listed.  

I would say no on your current system. Stay at 32 bit.
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I ran Windows 7 as 32-bit for a while on a system with 4GB RAM.  My system was only able to access and use a little over 3GB of that RAM, and it worked well.  However, when I installed Windows 7 64-bit, it was able to use all 4GB (or more, if available).  My hardware was all covered by 64-bit compatible drivers.
 
But if you wish to stick with old audio hardware that hasn't had a driver update in years, sticking with 32-bit will probably be your best bet.
 
As long as the rest of your PC hardware has 64-bit driver support, the other option would be to get an inexpensive modern USB audio interface that has drivers that fully support a 64-bit OS.  If it's an HP, check their website for driver downloads for Windows 7 64-bit.  It probably depends on the age of the system and when HP declared end of life for it.  If there are no 64-bit drivers available for your PC, then use what you have until you get a new PC.