Are Standards Pointless? no
Some excellent points have been brought up in this thread about why we should code in valid xhtml and css. Especially the point made about future compatibility. Eventually in the next generation browsers to come (hopefully the next releases) the the way browsers interperate code will be a standard thing saving developers huge amounts of troubles in making websites work in all browsers on all platforms. I think it was last week I read something about Opera and Mozilla colaborating to live up to the standards, I am not sure what Microsoft is doing but I am sure they will to. This means by validating your code now it will work in the new browsers to come.
In addition to that good points have been made about loading times in xhtml and css because of smaller file sizes, and also I think css caches background images better. Also the order the images load in help create an illusion of faster loading to
Why would you want to not make the site valid but make it work in all browsers? You can make it work in all browsers but still have valid code. I know that it can be frustrating some times especially when you are knew and the site validates but it doesnt work in all browsers. Many times though you dont have to use css hacks to get it to work and such. If you code it properly you should be able to get it to work in all browsers and validate. Some times hacks are needed. For example the other day I couldnt get transparent png-24 images to show up correctly in IE so I used a javascript to make them work in IE. This is an example of browser differences as IE doesnt support alphablending without setting it up right.
Now as for your portfolio I have only had a quick look at the code and the site in a couple of different browsers. the first thing I noticed in IE is that that side bar with the navigation and latest projects the style should be changed. What I want you to do on the following two styles: latestprojects and sidemenu is to change the following.
float: right; to float:left;
margin-right: 8px; to margin-left: 21px;
That will solve that problem and it will work in IE, mozilla and opera for sure and it is still valid.