Much as everyone loves Windows 7, not everyone has made the move yet. Plenty of folks are clinging to Windows XP for dear life, while others just didn't see enough reason to upgrade from Vista. After all, it's not like Microsoft is giving Windows 7 away for free.
But reader Vito is ready for a change, and he wants to know if he'll have any problems installing the newer operating system on his current PC.
Good question, Vito, and a good time for me to offer a refresher course in Windows 7 upgrading.
Let's start with your system, which you said is an HP desktop with a quad-core processor, 5GB of RAM, and Windows Vista x64 (i.e. the 64-bit version of the OS). Good news: you'll have no trouble doing an in-place upgrade to Windows 7. Just make sure you choose the 64-bit version, as upgrades can't go from 64-bit to 32-bit (or vice-versa).
Basically, any PC that has sufficient horsepower to run Vista will be more than sufficient to run Windows 7. The two have virtually identical minimum system requirements, and your machine already goes way beyond those.
As for upgrading a Windows XP system, that's an entirely different animal. For starters, there's no way to do an in-place upgrade without third-party help (like Laplink's PCmover Professional). What's more, you might not have enough CPU and RAM muscle to run Windows 7 in all its glory. Sure, a few upgrades might help, but for most XP users I really recommend buying a new system. For as little as a few hundred dollars, you can get a faster, better-equipped machine that already has Windows 7 installed.
For more on this kind of upgrade, check out Lincoln Spector's How to Upgrade from XP to Windows 7 and my own Three Ways to Upgrade Your Windows XP Computer to Windows 7.