I has discober somthing that´s may be help you like me (I home many people)... ... in internet I has read that´s if I install sql native client 2008 I work the same for SQL 2000, SQL 2005 and SQL 2008 and I can connect php easy whit the mssql_conect() function and yes it works fine with it but sorprice works my conection but stop to work my mantenence plans and Management studio (my god) what happen oviusly I don´t take care till 2 days after what I see the backups didn´t happen then I has seen when I try to use Managemen studio:

An exception ocurred......

additional info...

Could not load DLL xpstar90.dll or one of the DLLs reference....

then I try updating MSSQL SP2 this give me the tip because this can not connect at the server and the reason say some think about nativeclient then I remember the last backup was the same day I change the native client I uninstall the 2008 native client and reinstall the 2005 and voala it works again may you do not do some thing like me but may be is you reinstall the native client 2005 it fix the problem like me

😉