Sql-server – SQL server windows authentication through network

I am using sql server 2008 r2.There are about 50 pc in my office connected in network by using LAN.In a sql server 2008 r2 express(installed in windows 8) i have created all users windows account with same name as their name in their PC and then created windows authentication user in sql server. Now all the users are able to connect to sql server using windows authentication through SSMS.

But now i am trying implement same for the another SQL server 2008 r2 express which is installed in windows xp sp3. So i created one windows authentication user of network PC. But it is not working when i try to connect to sql server using windows authentication from network pc message comes like "Login failed for user 'PC91\Guest'. " It is not recognizing the windows account of my pc. why it happens? Please tell me a solution.

UPDATE:

SQL server and browser is running and sql server is already configured to use remote connections.Also i can ping the PC.

My doubt is is it allowed to connect sql server in another pc by creating same account as in sql server installed PC?

Let me explain what i did below:

In sql server installed pc(windows XP) i created windows login 'test'.Then i created sql windows authentication login using 'test' windows account.

In another PC i created windows user account 'test'(same as in pc having sql server,with same password) so that i have same user account in both PC. Now from this PC ,i connect to sql server of another PC by using windows authentication('test'). But it worked properly for sql server which is installed in windows 8 and windows 7.But for the sql server installed in XP it didn't work(I tried in two instance in two different windows XP machine). So i doubt if this feature is allowed in windows XP or i am going wrong in anyway(may be any settings missing)?