I used a PII 400Mhz with 256 Ram for years recording full bands. 16 tracks was not a problem. No Real Time effects though had to use "destructive" effects.This was my setup until about 5 months ago.
Your new to the program. Use the computer your familiar with and do some music. Learn BIAB & Real Band. When your really good at both then maybe shift to the new computer SLOWLY. If you don't you'll get frustrated and spend all of your time trying to fix computer things and not know if it's the machine, the program or you.

John
ESI Gigaport HD+
Lenovo Turion II /4 Gig Ram/ Win7x64 be
15.6" Monitor
"The only Band is a Real Band"
www.wintertexaninfo.com/BANDS/JohnnyD.php