My dad's got an SR300, and he's been playing for 25 years. I don't see how you could go wrong with one of those, especially as a beginner. Other than that I'd recommend a Squier Jazz bass.
Quote by Andron17
Go away, I have an erection.

Bassist for Half My Kingdom.
The SR300 is a fine starter bass. You should also check out the Squier Vintage Modified Precision and Jazz bass, the Squier Classic Vibe Precision and Jazz, and the Peavey Millennium BXP.

Do you have an amp already, and if not, whats your budget for one?
Composite Aficionado

Spector and Markbass
My girlfriends dad has one, its an extremely nice bass. I plan on him offering to sell it to me eventually, he just doesn't know it yet anyways, its a great bass, has a very nice, transparent tone that works great for about anything. Just make sure to try an Ibanez at a store. Any of the SR series would do the job, they just have some odd necks compared to your average bass, but I love them, so do lots of others, you might not. Make sure you test one out first.
SR300s are amazing starter basses in my opinion. They are very versatile, from thumping/pulling to melodic ballads and everything in between. They are really good. The neck is super thin and the action is very low, not many people like thin necks, but seeing as you are a guitarist, you'll probably enjoy it.. Throw some DR Hi-Beams on it and you have yourself a very nice sounding bass.