Before you start, what is the CPU speed and how much RAM memory do you have installed? I just answered your other post a moment ago... 90% of Windows 98/ME machines will not support Windows 7 until you upgrade them a lot. If your system has less than 1GB of RAM memory, then you cannot install any version of Windows 7.
If you upgrade your system to have more than 1GB of RAM and your CPU is above 1GHz, then you can install Windows 7 Home. I do not recommend Pro or Ultimate because they will be more taxing on the limited hardware. Also, you will not be able to directly upgrade Windows. You will have to do a fresh install, meaning wipe out the hard drive completely and then replace it with Windows 7. So you will lose all your programs and documents. You will need to back up everything before you start.
Chances are, if you have a computer that's running Windows ME, it's not going to support Windows 7. You're talking a 10 year old computer running a modern OS. You could upgrade it until you're blue in the face, and you're still going to be out of luck. Something that age is.....probably a P3 / Low end P4 / AMD Athlon 900-1600, running maybe.....128mb RAM, probably has a 10gb'ish HDD. None of which will even install Windows 7. The CPU *might* meet the requirements for Windows 7 but the rest of the system will prevent you from doing it.
It's time to invest in a new system if you want Windows 7.