Problems installing Windows 7 RTM

Hi,
I´m new at this forum, and my English isn´t very good.
Well. I tried to install Windows 7 build 7600 x64, but I really have a problem.
In one partition I have Windows Vista x32 English, and in an other partition I tried to install Windows 7 7600 RTM x64 English.
The installation was perfect, but with one problem.
After installing, I didn´t type any Serial number.
Than, I put my name as administrator, but I didn´t use any password, because I´m the only user of this Computer, and I like a quick login. But after all confirmed, opened a new window to put my login name and password. o, I put only me name because on installation I didn´t type any password. But I receive the message, that my login or password are incorrect.
I tried a new clean install, but this time using password. Now, my name is displayed on the login page, but typing my password it says that is is incorrect.
I ttried three other times to install W7 and used 3 diferent ISO, but nothing. It is still the same error.
Can someone help me?
thanks

Use a different user name. Do not use "Administrator."

I don´t use the name "ADMINISTRATOR".
I´m the only user of this PC.

During the installation, when I don´t type the username and password, I will use the quick login witout the display of the username.
But it shows the display without my name. So, I have to type my name and password.
And it shows, that my username or password are wrong. But I didn´t use any when I installed the OS.
So, I tried a fresh install and this time, I typed the username and password.
This time, the display appeared with my name, but the password is wrong.How can this happen?

Is it possible that I can´t use my Windows Vista x86 with the Windows 7 x64 ?
May be any conflict with diferent bits software?
thanks

I'm a bit confused, as in your first post you say:

I´m the only user of the Computer.
So, After the installation finishe, I need to type a users name and a computer name.
I did this.
But I didn´t use any password, but trying to make the login, I need to type user name and password, but I don´t have any password, only the user name.
Exist the possibility, that my W7 x64 doesn´t work, because my Windows Vista is x86 ?
Both are on the same Hard Drive in diferent partitions.
I read, that only same bits (x86) or (x64) can work on the same HD.
Is it true?

I am also confused.

When I install, I don't put in a password.

I don't ever need to log in.

Yes. After installing Windows 7, I don´t put any password.
This is my problem.
Without any password, W7 displays the login window, where I need to put my username and password.
But it says, that the password is wrong. How can it be wrong, if I don't use any...

I'd suggest just installing it again, as if you haven't been able to log in yet it won't make any difference if you do a fresh install.

Thanks for the answer.
But I still tried 5 fresh installs.
I also used another HD, but I have still the same problem in not to log in.

This is plain and simple: You're doing something wrong. This behavior is not some unique bug that you've discovered in Windows. You're either using the wrong user name, or you're setting a password and not realizing it.

Follow my instructions carefully:

STEP 1 -- ENTERING A USER NAME:
Enter the user name you want to use to log into the computer in the TOP BOX on this screen. Again, this is your user name. Do not use "administrator."


STEP 2 -- SETTING A PASSWORD:
If you do not want a password, do not enter anything at this screen. Just hit next and go on to the next page.



Long story short
If Windows is telling you that you have an invalid password, it's because you set a password and you're giving the wrong one.