Sounds like you either have the PS3 connected to a different router than your PC, have them connected differently, have a problem with your router/modem, or else you have some other issue with YOUR set up, as I get the exact same download speeds (about 6000kb/s) on my PS3 via WiFi as I do my Laptop via WiFi connected to the same router... which as anyone who understands how these routers and WiFi adapters work can also understand why this is the case.
Another thing I find is if people only ever download things like updates and stuff from the PS Store on their PS3 it does appear slow due to traffic experienced on those servers. I have found my PS Store speeds are almost double if I wait until Friday or Saturday. And update 2.40 took about half the time because I caught it at 6:00 AM instead of the end of the workday, like usual.
And the PC downloads may seem faster because that is obviously running on a different server, as it isn't available for as much as 24 hours sometimes. And because most people just update the PS3 directly via Internet that server isn't seeing nearly as much traffic.
When I first got my PS3 I thought that the download connections were slow too, but when I loaded up a Web site and tested downloading files from other places it went fine. A Speed Test even confirmed that the speed between PC and PS3 were very similar. The PS3 was slightly slower, but it wasn't a noticeable difference.
So, another thing some may want to keep in mind is that perceived speed may have more to do with servers elsewhere than the machine itself.
Seeing as how PCs set up for gaming run much,much more RAM than 256MB as well as 2+ Ghz P4s, 256 MB seems to be a REALLY small amount of RAM compared.
This comparison just doesn't even work. PCs vs consoles can't be compared looking at system specs. PCs have to run Windows and all the crap that comes with it in the background while you are gaming. None of the consoles have a system draining OS to worry about so many times they can actually devote more resources to a game than many gaming PCs.
You even mentioned that your PC needs a diagnostic check and defrag. Ever notice that consoles don't need that? They don't run Windows.
Heck, even comparing a PC to a Mac based on specs alone is deceiving because a Mac doesn't need to have as much extra resources available for the OS to abuse.
Some of my PS2 games seem to tak longer to load between screens and the like than they did on the PS2, and some of the PS3 games take a rather long time ( or it would seem to me) to load from one function to the next such as going from set up to say, into the game.
Are you running an 80GB? That is suing software emulation for PS2 games and that will add some time because it has to precess the game data going out in a way the PS3 can use and then input coming in has to be processed in a way for the game to recognize.
My 60GB has a barely noticeable difference.
And PS3 games are, by and large, much bigger than many other games. I mean, supposedly the audio on Heavenly Sword alone is bigger than a traditional DVD. Part of this is also due to being region free. Some games just go ahead and include multiple language tracks all at once. The increased capacity of Blu-Ray means bigger and better games, but it also means some extended processing time to get through it all.
So I really do want to know if the PS3 is capable of having its RAM capacity upgraded or if its just a fixed amount. RAM has nothing to do with download speed, BUT the download speed and and in a few cases load speed of games are a couple things I wonder can be sped up.
As the system is far from being tapped I doubt increasing RAM at this point will do any good. As I said above increased data capacity is leading to longer load times. That can only be sped up by faster drives.
The reason many offline games require hard drive installs are because they are attempting to avoid increased load times caused by having to search an entire BD. Some of this is also a developer laziness issue too, as apparently properly organized data on a disc will achieve a similar result.
Also, I know you play Warhawk, and I can guarantee that if your PS3 was suffering slow connections to the degree you are appear to be saying that you wouldn't be able to do that. Trust me, I know what happens to Warhawk when my wife loads up a Myspace page on the PC. <Server Disconnected>