Out of the 3 Toshibas you linked, eg6, I would spend a little more and get the Pentium with the extra RAM. All 3 have the same speed/size hard drive, but the extra processor power and ram will make a noticeable difference in day to day use.
Also, Toshiba is one of the better brands, if I were looking to buy with security I would be looking at Toshibas. HP getting out of the home PC market is an ill omen for their customer service, but since I work on my own I would be taking advantage of the discounts.