check size of users "home" folder

I work at a edu. facility. and I need to make a applescript that check the size of the users “home” folder at login. I have tried with the following script. I run it from the login items in the system pref. But something is wrong, can you please help…

tell application “Finder”
set username to name of home
set using to round ((physical size of home) / 1024 / 1024)
tell application “Finder”
if using > “4000” then
display dialog ("Hey… " & username & " You use too much diskspace! You use " & using & “MB your quota are 4000MB”) with icon stop buttons (“ok”)
display dialog “welcome”
end if
end tell

    end tell

end try

(size of (info for (path to current user folder))) / (1024 ^ 2) & " MB" as text

Thank you very much!

Just for my knowledge…what´s the differens?

No great differences… It is calling two “standard additions”’ commands: “path to” and “info for”.
Actually I prefer this mode because I’ve been having some problems with the Finder and I like avoid “tell” blocks allways I can… But your version works also fine:

tell application "Finder" to set using to round ((physical size of home) / 1024 / 1024)
if using > 4000 then --> compare number better than string
     display dialog "Hey!"
     display dialog "Hi!"
end if