Dot net 3.5 framework sp1 and family update setup error



hi all

my system is windows vista 32 bit sp1.whenever i am using windows update to install imp. updates dot net framework 3.5 sp1 and family update is giving x0643 error .After going through the suggestion given for this error at microsoft i did try to manually install it but it gives set up error with desc. and log as below.Please Help:

Microsoft .NET Framework 3.5 SP1 has encountered a problem during setup. Setup did not complete correctly.

Problem signature:
Problem Event Name: VisualStudio8Setup
Problem Signature 01: 35101
Problem Signature 02: 3.5.30729.01_ORCAS_X86_NET
Problem Signature 03: CBS
Problem Signature 04: INST
Problem Signature 05: F
Problem Signature 06: gencomp750,{61040379-156d-4ece-b126-ea395a3b2
Problem Signature 07: BASERET_UNKNOWN
Problem Signature 08: -
Problem Signature 09: -2145124330
Problem Signature 10: WUSA
OS Version: 6.0.6001.
Locale ID: 1033

Additional information about the problem:
LCID: 1033

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error log:
[06/23/12,23:57:04] Microsoft .NET Framework 2.0SP1 (CBS): [2] Failed to fetch setup file in CBaseComponent::PreInstall()
[06/23/12,23:57:04] setup.exe: [2] ISetupComponent::Pre/Post/Install() failed in ISetupManager::InternalInstallManager() with HRESULT -2147467260.
[06/23/12,23:57:04] setup.exe: [2] CSetupManager::RunInstallPhase() - Call to Pre/Install/Post for InstallComponents failed
[06/23/12,23:57:04] setup.exe: [2] CSetupManager::RunInstallPhaseAndCheckResults() - RunInstallPhase() returned a NULL piActionResults
[06/23/12,23:57:04] setup.exe: [2] CSetupManager::RunInstallFromList() - RunInstallPhaseAndCheckResults failed [2]
[06/23/12,23:57:05] setup.exe: [2] ISetupManager::RunInstallLists(IP_PREINSTALL failed in ISetupManager::RunInstallFromThread()
[06/23/12,23:57:05] setup.exe: [2] ISetupManager::RunInstallFromThread() failed in ISetupManager::RunInstall()
[06/23/12,23:57:05] setup.exe: [2] CSetupManager::Run() - Call to RunInstall() failed
[06/23/12,23:57:05] WapUI: [2] DepCheck indicates Microsoft .NET Framework 2.0SP1 (CBS) is not installed.
[06/23/12,23:57:05] WapUI: [2] DepCheck indicates Microsoft .NET Framework 3.0SP1 (CBS) was not attempted to be installed.
[06/23/12,23:57:05] WapUI: [2] DepCheck indicates Microsoft .NET Framework 3.5 ‘package’ was not attempted to be installed.
[06/24/12,00:23:55] Microsoft .NET Framework 2.0SP1 (CBS): [2] Error: Installation failed for component Microsoft .NET Framework 2.0SP1 (CBS). MSI returned error code -2145124330
[06/24/12,00:24:11] WapUI: [2] DepCheck indicates Microsoft .NET Framework 2.0SP1 (CBS) is not installed.