I'd go for the T5250, not a question of speed, but of cache.
The T2310 only has 1MB of cache.. The T5250 has 2MB (I'm guessing that's by core..)
I've bought my sister a Toshiba U300-TP3, and was also wondering between these two processor (T5250 with 1GB or T2310 with 2GB of ram), I've chosen the later, but I highly suggest you don't make the same mistake as I did.
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