They do have a 4gb version, i am not sure about the 64bit. That would be nice. They do have a 128gb SSD so that is pretty good. Stats below. I didn't know if you pulled out the hard drive of the ep121 that you would void the warranty, i wanted to upgrade the hard drive to a 128+. I love your idea of using a 128gb SD card. I am mixed on the SD vs Micro SD. The samsung will have micro SD, i don't know why they aren't listing it. I personally love the Micro SD, all of my devices use it. My Nintendo 3ds, my phone, my nook color.. i know i can do the adapter to use normal SD and i know that normal SD are cheaper and more reliable but to me i don't mind having just Micro SD.
The Samsung has a 11.6 vs the ep121's 12.1 screen. Samsung is brighter i believe.. but the viewing angles may be better on the ep121? Not sure about that. I like that the Samsung is almost 2 inches smaller in width. I plan to put this in my jacket so that will be helpful.
Another thing i really want to check out is the limit of the ram on the Samsung. If it can go over 4 gb's to 8gbs that would be awesome. Overall, performance in handling software is the most important thing to me. If the ep121 is faster, i will get that, but i don't think it will be. My knowledge on processors is very limited but i hear alot of great things about the samsung's processor and it is almost identical to their new samsung 9 series laptop.
Samsung Series 7 Tablet Specs
11.6-inch 1366 x 768 display
Active digitizer pen (Wacom)
400 nits brightness (extremely bright)
Intel Core i5-2467M processor (1.6GHz)
4GB of DDR3 RAM
2MP / 3MP front and rear webcams
light sensor
802.11b/g/n Wi-Fi
USB 2.0 port
Micro HDMI out
SIM card slot for 3G data
0.5 inches thick
2.03 pounds weight
7 hour battery
Samsung Series 7 Tablet Model pricing
64GB SSD + Windows 7 Home Premium $1,099
64GB SSD + Windows 7 Professional $1,199
128GB SSD + Windows 7 Home Premium + Dock + Keyboard $1,349
128GB SSD + Windows 7 Professional $1,349