I do not have any expierence using Newegg Preferred Account or Bill Me Later, but I do know that applying for lines of credit(Credit Cards) does get reported and may temporarly lower your score.
Check out this website for Clark Howard on CNN( http://www.cnn.com/CNN/Programs/clark.howard/
), this guy is very smart and the information you want about your credit and financials will all be there.
This is a annual free credit site reccomended by Clark Howard:https://www.annualcreditreport.com/cra/index.jsp
Hope this helps.
One other thing: •Interest will accrue at an ANNUAL PERCENTAGE RATE of 25.99%
. If you do do this make sure you pay your balance before the 6 or 12 month period is up.