Get R2011 64bit for free (and save it somewhere safe for the future) if you can't drop to Win8 or Win7 32bit, you should be able to find it at the Autodesk Customer Service Virtual Agent:
•In the preferences or options area of your preferred browser, remove pop-up blockers and allow access to all *autodesk.com sites.
•In the preferences or options area of your preferred browser, delete cookies, temporary internet files, and history.
1. Turn off your personal firewall or VPN, if you use one.
2. Disable UAC
3. Close and reopen your preferred browser.
4. Go to http://autodesk.creativevirtual15.com/autodesk/bot.html?isJSEnabled=1&businessArea=Root.Front%20Desk...
5. Select the choice "Download Links".
6. Select your product, then variant, then version as applicable.
7. You should now be presented with the choice to download your software.