I don't think it's possible (at least for Lansweeper) to detect whether a processor is 64-bit capable on a Windows XP machine unless it's running Windows XP x64.
There's a built-in report called "Computer: 64 bit processor but 32 bit OS installed" that I tried tinkering with, but I couldn't get it to show Windows XP machines.
For the other information you're looking for, you can just click on a specific domain in the "Domain Overview" and that will give Name, OS, Memory, CPU, etc.
Also as a note, there is a 32-bit version of Windows 7 that only has a 1GB memory minimum requirement. We have quite a few machines running this with only 1GB memory and they seem to work great for non-CPU intensive day-to-day activities.