Cannot get rid of SQL server 2005 Developer Edition Installation

I cannot uninstall the SQL Server 2005 Developer Edition. I have run the uninstall from the control panel forALL of the SQL Server 2005 components.They are no longer listed in the installed programs list. I have done the uninstall with both the Control panel and the command line.

When I try to install SQL server Express (Downloaded from the web last night) It will not install. The error message is: TITLE: Microsoft SQL Server 2005 CTP Setup
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There was an unexpected failure during the setup wizard. You may review the setup logs and/or click the help button for more information.

For help, click:http://go.microsoft.com/fwlink?LinkID=20476&ProdName=Microsoft%20SQL%20Server&ProdVer=9.00.1116&EvtSrc=setup.rll&EvtID=50000&EvtType=setup%5Csqlsetupactions.cpp@ActivateLoggingAction@sqls::ActivateLoggingAction::perform@0x80070643

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BUTTONS:

OK
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When navigating to the web site via the help button the message that is displayed is:

Details
ID:	50000
Source:	setup.rll
We're sorry
There is no additional information about this issue in the Error and Event Log Messages or Knowledge Base databases at this time. You can use the links in the Support area to determine whether any additional information might be available elsewhere.

I've been trying to get rid of this installation for almost a month now, so that I can install the SQL 2005 Express edition for use with web security. I've done everything except wipe the machine and reinstall the operating system.

Can someone tell me how to uninstall the thing via the registry or something?

[3154 byte] By [OtisMukinfus] at [2007-12-16]