Dude upgrade that preamp before thinking about speakers. Pretty much any built in preamp is automatically shitty. A Cambridge 540p phono stage will do the trick nicely for only 80 bucks.
Are you looking for hi-fi tower speakers or computer speakers? They're both completely different markets.
If there's one thing I've learned from my time studying audio engineering and working in a studio, it's that the most significant stages of the signal path are from the bottom up. Meaning your low-budget turntable is pretty much gonna make your whole system sound low-budget no matter what speakers you get. What model turntable do you have exactly?