Konami released a ton of screenshots that let you compare the old and HD remakes of the Metal Gear Solid games that comprise the Metal Gear Solid HD Collection.
Check the gallery to see how the PSP version of Metal Gear Solid: Peace Walker and the PlayStation 2 versions of Metal Gear Solid 2: Sons of Liberty and Metal Gear Solid 3: Snake Eater match up with their PS3 HD counterparts. The collection is also coming to the Xbox 360, but just imagine it will look exactly the same for sanity's sake.
Looks pretty good, doesn't it? The biggest difference comes from Peace Walker, of course, and some of the Snake Eater shots look a bit stretched in HD. But otherwise, even the PS2 shots still look more than playable enough.