I bought a Dell Inspiron about a year and a half ago.  It came with a GeForce GO 6800 and I wanted to upgrade it.  There are ways to do it, but for the most part, it's extremely difficult.  You can find many laptop video cards on Ebay but installing it is rather tricky, especially with all the different chassis.

The XG is an option, but I'd really recommend checking with the system vendor.  I can build desktops with no trouble but looking into upgrading my laptop's video card gave me a lot of hesitation and I didn't do it.  I suppose time will tell with the external video cards.

It sounds like you are using a wireless router, but it's connected to your PC via a blue CAT5 cable which is a direct connection.  With direct connections, it's hidden in the control panel and you won't see it unlike wireless connections.

You have the option of going wireless, but you'll need a wireless card which your base model doesn't have, and you don't recall installing one.  Open up network connections from the start menu and check the settings.

In most games I've played, the answer is no.  Supreme Commander made a huge difference though.  However, if you multitask, you'll definitely notice it.  I though hyper-threading was great, but two cores is awesome.

But I must say that having the option of encoding while going about my day is amazing.  I never actively think about it anymore, but I used to wait until I went to bed to do any sort of lengthy process.  Now, I'm encoding movies to mp4 formats while I'm gaming.

And of course it is also the future.  Most games aren't coded for taking advantage of more than one core and it's quickly changing. 

Do you see a blue screen or any thing else before the restart happens?

I'd try opening the cases and making sure the processor fan is cleared of any dust. While you're in there, check the other fans as well.

A few years ago, I had random restarts. The only time it wouldn't restart if I booted a dos prompt. I even tried to reformat. It restarted because the processor got too hot. After I cleared the cooling fan, the problem stopped.

If that doesn't work, you could try a bootable linux disc and see if you have that problem in Linux. It'll boot from the CD.

Good luck.

Try running MSCONFIG (Run then msconfig) and under the Startup tab, disable everything.  I'm very picky when I start Windows.  Do you still get the same lag?  If not, I'd start adding back stuff you need and checking for the lag.  You might be able to pinpoint what's causing it.

I'm running 32 processes right now with Internet Explorer, Outlook, Word, and a few other programs up.  But again, I like the minimalist approach, as it keeps Windows feeling quick.

I've had great success with Logitech's Play Link.  Installation couldn't be simpler, nothing to configure.  It's about $20 online, though it can be found cheaper.

The only downside is that the maximum speed is 1.5 Mbps which hasn't affected me at all with games, just the time to download demos :cry:

While not exactly a wireless adapter, it's a cheap solution I use.

Fight Night 3 was easy, especially if you turn down the difficulty.  Star Trek Legecy is moderately easy as well.

If you're willing to devote some time to beating them, both Marvel Ultimate Alliance and Enchanted Arms are easy to gain Achievement Points in.  A quick play over the weekend should net you a decent amount of points.