So far when you change from ANY Windows OS from 32 to 64 bit it's never an upgrade but a clean install.
You are likely to find that this system will run Windows 7 64 bit but be sure to look for all the drivers for Sound, Video since sometimes Microsoft doesn't get them for us.
Can I share my big secret to such upgrades without the trauma? Ready? I remove the old hard drive and carefully put that in a safe antistatic bag far away from the upgrade zone. Slip in a new blank HDD and try to install Windows 7.
Bob
Current system has AMD Athlon 64(V) 3800+Processor,939 Socket chipset, ASUS A8N-LA, with 3GB of RAM factor set 32 bit. Can I upgrade to Windows 7 Home Premium 64 bit since my system specs says it is Vista ready? I don't do a lot of multitasking just considering the simpliest upgrade without buying a new system.

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