Yes, this is quite normal for XP. i usually have 4 to 8 instances is svchost running on my XP computer at any given moment.
The Svchost.exe file is located in the %SystemRoot%\System32 folder. At startup, Svchost.exe checks the services part of the registry to construct a list of services that it must load. Multiple instances of Svchost.exe can run at the same time. Each Svchost.exe session can contain a grouping of services. Therefore, separate services can run, depending on how and where Svchost.exe is started. This grouping of services allows for better control and easier debugging. http://support.microsoft.com/kb/314056
Vista does this differently as i can find only one instance of svchost running on this laptop computer in task manager.