I had a similar problem when dealing with my father about my laptop, which ended up being a low end 15" MBP with an upgraded hard drive. My dad always asked me if the $500 or so Celeron laptops that Best Buy has were "good enough" and always grumbled when I said "No, they aren't." Luckily, I had my mother to talk to, who gets computers. Reguardless of whether your mother is a computer person, if she isn't involved in this decision yet, get her involved.
Step 1 for getting a better computer: Get your mother involved on your side.
LOL, I agree!!! I showed my mom this, and she's like "Wow, why don't post something on there saying you did that too!" She was joking of course, but she does know when I want something, I try to sweet talk my her. It's quite suprising tho, when I asked my father for a new SR MBP, I didn't have to turn to my mom... cuz I desperately needed one for the field of work I'm getting in.