How do I back up the old BIOS and revert to it if necessary?

It isn't necessary to back it up.  Go here:  Vostro 200 BIOS.  The page containing the latest version should appear when you click the link.  If you don't like it, all earlier versions can be found by clicking the "Other Versions" link to the right of the flash file title.  Simply re-flash using the older version of your choice.  I've never flashed a Vostro, but some files used on other models in the past warn you that you are flashing an older version than is present on the machine.  Usually all you need to do is confirm that is what you want to do.

michael88s,

You should have no issues, I recommend you read http://www.dellcommunity.com/supportforums/board/message?board.id=dim_bios&thread.id=61309

Before you start the update just make sure you shut down any programs that may be open or running in the background. the only thing you should have connected to the pc should be your mouse, keyboard and monitor of course. I was a little paranoid when I did it and I even disconnected my speakers.

It shouldn't take more than two minutes, just don't touch anything until the pc tells you it is done.

Follow the instructions exactly and you will be ok.

Thanks guys,

I expect I'll be doing the upgrade in the next day or so, and I'll post then.

Regards,

Michael

Mars1100 and JackShack,

I just wanted to thank you both, flashing the BIOS and the processor upgrade both went fine.

The only snag was something ridiculous- the new fan/heatsink: instead of screws it has these weird (to me) lower plastic pieces- pointed with what appears to be a a stop, and you're supposed to turn upper plastic pieces 1/4 or 1/2 (?) turn to secure each of the four. The manual has a totally different diagram. All I could figure was maybe you're supposed to push each end down until it clicks in, then turn the screw. The whole system didn't inspire confidence.

So I went with the old fan/heatsink, and since I couldn't find any thermal grease, I took the grease off the new fan with a knife and used that- not being cheap, there's no computer supply store nearby, and I just wanted to get it done. 

Thanks again!

Michael

For future reference, you can find previous versions of BIOS, drivers, etc for various Dell systems on their ftp site.

Note: I haven't verifed that previous versions of BIOS for this particular Vostro system are available, as of today.

Ron 

LOL, michael88s that is one I have not heard yet "I took the grease off the new fan with a knife and used that".

Most people don't use the new heatsink for that purpose(plastice push pins), I've seen a few stick with their stock Heatsink.

 If you are sending this message I guess it worked and that is what matters.

YOu may want to get some fresh thermal grease on there as soon as possible as it helps to control heat,

try Radio Shack, Best Buy, CompUSA, Frys, Circuit City just to name a few.

If you live in my area I have some extra I can give you, if you like. (IM me or send a private message or whatever it is called here)

Congrats on the upgrade.

RoHe,

That ftp site looks like a handy one to have, thanks.

Mars1100,

I'm cool with the thermal grease thanks. I see that you're in Florida- I'm in NY myself. If you're a baseball fan I guess you've been enjoying the Rays...

Michael 

I am a former New Yorker and I am a Yankee fan, therefore I am not enjoying this season too much.

Glad to see your system is running A OK.