Hey Bryan, you already have all the answers you need from your first two posts: the ones from Ramarc and Watzman.
Basically, most programs from XP will work just fine with Windows 7. Of those programs that are older (designed before Vista existed) if any have a problem running correctly, they can be told to run in a compatibility mode. This includes modes for:
Windows Vista (Service Pack 2)
Windows Vista (Service Pack 1)
Windows Server 2008 (Service Pack 1)
Windows Server 2003 (Service Pack 1)
Windows XP (Service Pack 3)
Windows XP (Service Pack 2)
Windows NT 4.0 (Service Pack 5)
Windows 98 /Windows ME
Any of these can be chosen by right clicking the program that isn't working properly; then in the drop down menu go to 'Properties'. Under the new windows that opens go to the 'Compatibility' tab and check off 'Run this program in compatibility mode for:' and choose 'Windows XP (Service Pack 3)'.
Sometimes a certain legacy program might not running exactly right because it's asking to be at an admin level (which Vista and 7 restrict to protect you, and for good reason), in that case under the same 'Compatibility' tab you can check of the box that says 'Run this program as an administrator'.
Even though it's great that these features exist and it's good to know how to access them, for the majority of programs you won't have a problem running them, and if you do, Windows 7 will generally automatically ask you if you want to run it in a compatibility mode/reinstall the program with the correct compatibility.
And yes, there is XP mode (which is not the same as compatibility modes) which virtualizes running Windows XP to give full compatibility, but this really is designed for Small Businesses that have special software written specifically for their company, and will only run in an XP environment. XP mode is not designed for consumers and not needed by consumers either. It's unfortunate that consumers hearing about XP mode think they would need it, but honestly I've never run into a program that didn't run correctly in Vista or Windows 7. Have some programs had to use a compatibility mode? Yes, some have, but that's exactly why it those compatibility modes are there, and after checking off that compatibility box I never had to think or deal with that program again.
So, use the 'Upgrade Advisory' and compatibility tools that Ramarc your first replier linked. They will show you what programs/hardware will work with Windows 7, and any issues that might exist. It's said the Windows 7 is actually more compatible then Vista was with older software, I don't remember where I first read that or the data to back that up, but it's an interesting thing to think about.
Also, on the Windows 7 DVD install disc, there is a great tool called "Easy Transfer" this allows you to migrate your files, settings, and users from your old windows to windows 7. This does not include programs, but once you've completed the migration, a report will appear that will have a list of all the files transferred, and a report on what programs you had installed before, if they have been installed yet, and information the programs and the companies they made them, such as a link to download the program (if applicable). One of my favorite parts besides the software company links, are that it continually checks to see if you've installed these programs, and you can access this report at any time. So for me, I have a lovely list of everything I used to have installed and I can systematically install them at my own pace, I can close the report and open it again at a later date, I can choose possibly not to go back and install a certain program, and if I do want to install a program I won't forget any of them. The 'Easy Transfer' works by copying these files and settings to a USB drive, by network, or by an 'Easy Transfer Cable'. If you are upgrading your current machine to Windows 7 you will have to use a USB drive to save the file and reload them, as the other two options are for moving the file directly to a Windows 7 machine (ie: if you bought a new computer and wanted to move your files and settings from your old computer to your new one). As the name suggest it is really easy, while allowing you choice on what files you want to migrate. If you are moving a lot of files it may take some time to copy and then recopy the files back to Windows 7 but the process is automated and simple to use, so you can leave and come back later.
Overall, there are a lot of ways make the process from moving from older Windows to Windows 7 easy, and let me say, you'll be glad you made the move; Windows 7 is just great.
Good Luck and hope all goes well.