When you say files and components, that excludes apps - which must be reinstalled. However, everything else (docs, MP3s, JPEGs, etc) you can backup and restore as needed. What to do depends on how/if you have your HDD(s) partitioned.
I always partition my HDDs to create a primary OS partition. On that partition, I ONLY install the OS. Why? Because, I can create image backups and restore as necessary without endangering my treasured data - which resides on different partitions or HDDs. After all, it is primarily the OS that may become corrupt and need to be "cleaned," reformatted, or restored - something that is rarely required for data partitions (malware attacks the OS not JPEGs of your dog).
So, backup your treasured data, install Windows 7, reinstall your apps, then restore your data files if they were inadvertently altered or wiped by the Windows 7 installation.
Which version: x86 v. x64? Well, most apps are still written for x86 so that will give you the least headaches. What headaches? Finding/updating drivers for x64. The issue is getting better as more developers are creating x64 drivers for their apps but there is a way to go. The immediate primary advantage of x64 is the ability to access greater than the 3.8 or so GB RAM limit enjoyed by an x86 OS. Do you need/have more than 4GB of RAM?
Depending on your needs, you may very well be well served by the x86 OS and will not likely notice the difference between it and x64. Driver issues WILL, however, become a part of your life with the x64 OS.