You can replace it (but from another OS starting).
Check for viruses the file C:\Windows\system32\dllcache\svchost.exe. If it
is healthy, you can just copy it to C:\Windows\system32\svchost.exe and
replace the file that has a virus.
If it's not healthy, copy it from you distribution disk. i386/svchost.ex_
It's a archive file you have to extract it.
Use the command:
expand SVCHOST.EX_ SVCHOST.EXE
Don't forget replace all the copies af the file
(C:\Windows\system32\dllcache\svchost.exe and
C:\Windows\system32\svchost.exe)