Go for the 4GB, believe me, you will need it, you will fill it up fast. I have a LONG list of software I keep on my 4GB, all the stuff I use all the time. Here's what I have:
Active Virus Shield
Ad Aware
Adobe Acrobat 8
Analog X Tools
Angry IP Scan
Autopatcher Vista
Autopatcher XP
AVG Antispyware
CableNut
CD BurnerXP Pro 3
Cobian Backup 8
Comodo Firewall
CPUZ
CrapCleaner
Driver Cleaner Pro
Drivers - Long list of most used one's
DVD Fab Platinum
Emule
Erunt
Everest
Firmware - most popular router firmwares
Firefox - with a lot extensions
HijackThis
HotSpot Shield
IE Fixes - tools to repair IE
IE Pro
IE Spyad
Itunes
Izarc Zip
Java Sun
Jv16 Powertools
KAV 6
KIS 6
KAV 6 Updates (you can install them from here)
Kazaa Lite Resurrection
K-lite mega codec pack
Limewire
McAfee Removal tools - to remove McAfee products
Open office
Opera
Perfect Disk 8
Picasa
Power DVD
Slysoft CD/DVD Burning Programs
SpamBayes
SpyBot
SpySweeper
SpywareBlaster
Superantispyware
Symantec Removal Tools - to remove Symantec products
Sysinternals Programs
Trillian
TuneUp Utilities 2007
Tweak VI Basic - Vista tweaker
UltraVNC
Unlocker
Winamp
XP Antispy
X Setup
Your Uninstaller
That's my list, long. but a lot of good software I use on a daily basis.
