Hi,
Validate the page code? For what? This is by far the weirdest thing i have ever heard in this forum. I am serious.
Or you don't realize the main reason of w3c validator. That validator is exist only to guide the developers, what it suggests are not "must-to-do". It will guide you in case you did something wrong or forgot something while coding. Try to validate wikipedia.org,
www.amazon.com or even
www.google.com and see how many "critical errors" you will see. And don't worry, google indexing bots are cleaver enough to figure that out.
ALT tags are normally important, this is why the w3c validator warns and ask you to fix it. ALT tags for image are only used for search engines while they are indexing the pictures of your website (image searches of google, bing and yahoo) but that 1x1 transparent image... Of course google or nobody won't index that tiny image, because it doesn't even have color, it is transparent. So the ALT text is completely useless and not necessary. Indeed; google more cares about the "main content" that is around the picture to understand what that picture is about, instead of looking at the ALT tags.
You really don't need to do that just to get a "Well done job" from w3c validator. It will give you nothing. Are you a developer and is your client asking for that kind of thing specifically? If so, you can explain this to him in a nice way and stop wasting your time for validation.
Regards.
Support.