Thanks guys.
Additional info re infected files (filename, original location, virus) as follows:
1. bqxdihrdtzx.exe, c:\bqxdihrdtzx.exe, Win32:Trojan-gen.{UPX!}
2. dload.exe, c:\WINDOWS\dload.exe, Win32:Trojano 027 [trj]
3. exdl.exe, c:\WINDOWS\SYSTEM\exdl.exe, Win32:Exdl[Adw]
4. exdl0.exe, c:\WINDOWS\SYSTEM\exdl0.exe, Win32:Exdl[Adw]
5. exdl1.exe, c:\WINDOWS\SYSTEM\exdl1.exe, Win32:Exdl[Adw]
6. loader2.ocx, c:\WINDOWS\Downloaded Program Files\loader2.ocx, Win32:Trojano 874 [trj]
7. MQEXDLM.SRG, c:\WINDOWS\SYSTEM\MQEXDLM.SRG, Win32:Exdl[Adw]
8. optimize.exe, c:\WINDOWS\optimize.exe, Win32:Trojan-gen.{Other}
9. saaphook.dll, c:\WINDOWS\saaphook.dll, Win32:Trojan-gen.{Other}
Any further advice and some principles to follow very gratefully received.
pjfb