Thread: Power inverter?

ok i know that this way is not the way most people do it but i am not good with wiring stuff together so i am going to use and power inverter. i was going to use a laptop but it doesnt seem to have enough power its a ibm thinkpad t20 900mhz with 256 ram and 20 gig. when i run roadrunner it is very laggy and slow but does run it. heres what i have for a desktop

lillput 629 7inch touch
P4 2.26
gigabyte mb
gig of ram
nec 3520 dvdrw
wd 160gig hd
ati 256 vid card
with a 650 watt power supply going to change that to 250 or 300
do you think it will run on that power sup with an inveter thats atleast 350 to 400
thanks for any info