LOL like windows ME??? I doubt you computer will run Windows 7 it is a Windows 98 class machine. But if your going to try there is no way directly. You will have to upgrade to XP then Vista then Windows 7...
If you are compatible, you do not need to upgrade to each windows version, there aren't even upgrade versions like I think thently is thinking of. You just get w7 and install like any other pc, irrelevant of any other os version. Though I would assume such an old rig is not compatible.