Advise for Laptop Build

Hi I am building a laptop at dell.com for home use (some multimedia/video editing, regular everyday things like surfing the net and very little to no gaming). I designed the following build from dell for $1000 after using the $325 off $1300 coupon.

Inspiron 1520

[B]Processor:[/B] [B]T7500 [/B](2.2GHz/800Mhz FSB/4MB cache
[B]Screen:[/B] 15.4 inch display (1440x900) High Resolution, glossy widescreen
[B]VIDEO CARD[/B] - 128MB NVIDIA® GeForce® 8400M G
[B]MEMORY[/B] 1GB Shared Dual Channel DDR2 at 667MHz
[B]HARD DRIVE [/B] Speed: 120GB SATA Hard Drive (7200RPM)
[B]WIRELESS NETWORK CARDS[/B] Dell Wireless 1390 802.11g Mini-Card
[B]Battery[/B]: Lithium 9 Cell battery.
[B]SOUND OPTIONS[/B] High Definition Audio 2.0

Comes with a standard cd/dvd writer and integrated webcam and bluetooth. I am just going to buy 2gb RAM on the outside and install that to get the RAM to 2GB.

I just have a few questions.

1) Is there a big performance difference between 7200 rpm vs. 5400 rpm HD. I was told 7200 tend to heat up more...will that cause problems for the system down the line?

2) For the wireless card, whats the difference between the Dell wireless 1390 802.11g card and the Intel 3945 802.11 a/g mini card.

Lastly any advise on if you think this is a good build and a good value. Should I pull the trigger or is it better to wait?

Thank you.