trojan maware also disables regedit & task manager

Hey Pls help i am fed up with formatting my c drive
(since the virus stops me from using net also)
I have trojan malware & some other virus (i don't know may be autorun.exe,.inf) they are in other drives(don't want to format them) more over when ever i run any software (saved in those drives) i get "registry & taskmanager disabled"
right now don't have any anti virus installed.
sooooooo pls help

Logfile of Trend Micro HijackThis v2.0.2
Scan saved at 12:11:09 AM, on 7/27/2009
Platform: Windows XP SP2 (WinNT 5.01.2600)
MSIE: Internet Explorer v6.00 SP2 (6.00.2900.2180)
Boot mode: Normal

Running processes:
C:\WINDOWS\System32\smss.exe
C:\WINDOWS\system32\winlogon.exe
C:\WINDOWS\system32\services.exe
C:\WINDOWS\system32\lsass.exe
C:\WINDOWS\system32\svchost.exe
C:\WINDOWS\System32\svchost.exe
C:\WINDOWS\system32\spoolsv.exe
C:\WINDOWS\system32\svchost.exe
C:\Program Files\Speed+\Client\ventc.exe
C:\WINDOWS\Explorer.EXE
C:\Program Files\Speed+\Configurator\ventcfg.exe
C:\Program Files\Speed+\squid\ventcsquid.exe
C:\Program Files\Speed+\squid\ventcdnsserver.exe
C:\Program Files\Speed+\squid\ventcdnsserver.exe
C:\Program Files\Speed+\squid\ventcdnsserver.exe
C:\Program Files\Speed+\squid\ventcdnsserver.exe
C:\Program Files\Speed+\squid\ventcdnsserver.exe
C:\Program Files\Speed+\squid\ventcdnsserver.exe
C:\Program Files\Speed+\squid\ventcunlinkd.exe
C:\WINDOWS\system32\wscntfy.exe
C:\WINDOWS\regedit.exe
C:\WINDOWS\system32\taskmgr.exe
C:\Program Files\TATA\SAM\sam.exe
C:\Program Files\Internet Explorer\iexplore.exe
C:\Documents and Settings\manu\Desktop\winlogon.exe

R1 - HKCU\Software\Microsoft\Internet Connection Wizard,ShellNext = http://www.tataindicom.com/sng01/
O4 - HKLM\..\Run: [Venturi Configurator] C:\Program Files\Speed+\Configurator\ventcfg.exe -nomsgbox
O4 - HKCU\..\Run: [SAMAccessManager] C:\Program Files\TATA\SAM\sam.exe
O9 - Extra button: Messenger - {FB5F1910-F110-11d2-BB9E-00C04F795683} - C:\Program Files\Messenger\msmsgs.exe
O9 - Extra 'Tools' menuitem: Windows Messenger - {FB5F1910-F110-11d2-BB9E-00C04F795683} - C:\Program Files\Messenger\msmsgs.exe
O17 - HKLM\System\CCS\Services\Tcpip\..\{EB17F070-9F6B-43AC-A4A3-2C855705EA00}: NameServer = 202.54.15.30 202.54.1.30
O23 - Service: Venturi Client (VenturiClient) - Venturi Wireless - C:\Program Files\Speed+\Client\ventc.exe

--
End of file - 1996 bytes

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thax a lot sir u helped me & my PC from this severe problem
i was really fed up with the problem & u saved me
i really appreciate ur effort & time u devotated
you really "ROCK" man..........!!!!!!!!!!!!!!