Vista Home 32 bit on Toshiba Laptop

I have a Toshiba Satelitte Laptop, it came pre-installed w/Windows Vista.
I've been getting a message about not being able to update for a while, but
mistakenly thought this was because of something I as the user had done, as
opposed to a corrupted file. Now, when I do want to go get an update, I'm
getting error code 80070490. I've looked up previous posts about this
message, and the general consensus is that the only way to correct this is to
"upgrade" from the original Vista disc. However, I didn't get a Vista disc
with my laptop. When I run my system install disc, I can't select Windows to
"update." In fact, the only option I can see that will probably work is a
full system restore, which will of course format and partition my drive,
losing all my data and programs. Please, does anybody know if in the last,
oh year or so, Microsoft has come up with a fix for this beyond that of going
to a disc that I imagine the vast majority of current Vista users never even
owned? Frankly, I find this whole issue to be downright deplorable and just
a continuation of Microsofts notorious reputation for buggy and shoddy
products. At this rate, I too might join the throngs of folks moving over to
Apple.