PC Hardware Performance
PC hardware performance can also play a role in determining how long does it take to upgrade from Vista to Windows 7. Processor, RAM, and hard drive speed can all have some effect on the upgrade process.
Your computer's processor, clock speed, cores, threads, and more, determine how fast your computer is able to complete certain tasks. Thus, if you have an older Pentium 4 processor, the upgrade is probably not going to be lightning fast. But then again, if you have an older Pentium 4 processor, most likely nothing goes lightning fast. The complete opposite of this would be if you have a newer Core i7 Processor. The newer technology is an obvious advantage in overall PC performance, which includes situations like this.
RAM is much more technical than many people would even care about. But for the most part, RAM makes running processes smoother. RAM also comes in several speeds, such as DDR, DDR2, DDR3, etc... RAM does not play a huge factor in how fast you will be able to upgrade from Vista to 7. However, 4GB of RAM will probably assist the upgrade slightly more than 1GB of RAM.
When you are doing an upgrade from Windows Vista to Windows 7, there are a tremendous amount of files that are being copied to specific locations on your hard drive. Hard drives come in several different speeds. For example, most desktop computers have a 7200 RPM hard drive. Some high-end PCs have a 10,000 RPM hard drive. The 10,000 RPM hard drive is capable of copying files at a faster rate. Alternatively, most laptop computers have a 4500 RPM hard drive. This would be significantly slower than the high performance 10,000 RPM hard drive.