Inspiron 6400/E1505 - Is this possible?

Sounds like ya got a good card there, mate. Mine was the top-of-the-line for the 9300 a year ago. It still kicksbum now a days: F.E.A.R., CS: Source, Photoshop, Half-Life 2...

What are you particularly disliking about it?

not possible at all. You can upgrade to a 256 MB X1400 card. That's about it

Here's what you do. Get a piece of high-grit (1000-ish) sandpaper, Arctic Silver Ceramique compound, isopropyl alcohol, and possibly a razor blade. Take the laptop apart, get the heatsink off of the video card. Use razor blade or fingernail to get all of the original thermal pad off of the HEATSINK. Use the alcohol to clean the GPU, don't ruin the GPU or you'll be ticked at yourself for a long time. Then, take the sandpaper and rub out the surface of the heatsink that is going to be touching the GPU, get it gooooood and smooth. You can get it almost mirror-like if you're patient enough. Avoid deep grooves, and thus avoid low-grit sandpaper. Clean the heatsink with the alcohol. Get a plastic something to cover your finger with, thermal compounds are supposedly really bad for you. Anyway, get a dab of the compound and put it on the heatsink. Rub it into the heatsink, don't just glob it on and leave it there like most people do. With the excess that will be stuck to your plastic-covered finger, rub a bunch of the compound into the top of the GPU, only touch the small piece of the GPU, not the big green part (haven't seen yours exactly, but it's probably green). Wipe it all off with a paper towel, and apply it again, use very little this time. After that, reassemble everything. Then, go to www.omegadrivers.net. Download and install the proper drivers. Inside the settings-advanced section, there is now a selection for overclocking. Turn it on (make sure you select 3d) and get optimal settings. It'll automatically overclock your vid card at decent speeds. You might want a cooling pad if it runs hot. I did this on my 9300 a year or so ago (long since sold it) and it ran B-E-A-utifully for a long time. Great speed increase. The video cards are dumbed down from the start, so it's like you've released it from an inhibiting cage, and it can finally be itself!

And, I think you're right, the nvidia is probably a better choice than the ATI. ATI supposedly has better picture, but on a laptop screen you won't notice, and nvidia is all about raw speed, plus they overclock better from my experience.

Actually Ive seen both the cards at work and I honestly feel the X1400 performs overall better than the 7300 Used in the 1505. The 7400 on the otherhand is where you would consider the Upgrade to really be and im puzzled why they didnt consider this in the first place considering that this card is used in smaller notebooks such as the M1210 and the latitude D620.

Personally, Ive always found ATi to have a little more juice. But its mostly personal preference. I haven't used an nVidia card since their FX series and those sucked big time.

You could do a heatmod on the video card to give it a little more overclocking capability but in reality, it won't do much unless you're able to keep it stable

You'd have to seriously research that. Most likely, the socket won't even be the same shape. If it is the same shape, the pinouts could be different. If those are the same, it's possible the LCD connector will be different. It's altogether possible, if not likely, that the laptops that have 7400s and the e1505 aren't even made by the same company. If you DID make it work, be sure to post a photo guide with part numbers and etc, as I'm sure lots of people would like to do it.

Sorry for the confusing what I meant to say was that Im puzzled that Dell chose to use the Nvidia 7300 Go as Opposed to the 7400go found in there other small form factor notebooks.