If you are comfortable with any brand go for Sony Ericsson w700i which retails for Rs. 12000 (thats the price I got you can get even cheaper now). I'd say its a better deal than K750i as you get a 256 MB Memory Stick (instead of 64), Walkman Player and what I like, a music cable with adapter to connect 3mm jacks like normal headphones or stereo (2.0 or 2.1) speakers. There are also a large number of softwares, themes, addons available for this phone on internet as it is backward compatible with K750i so it is the best deal you can get for that price. You will not regret this purchase over a Nokia if you are a audiophile like me, sound quality beats a Nokia hands down. I switched to it after I lost my Nokia N72 last month.
The only drawback is in some songs the volume can't be raised to very high (perhaps because of risks of lawsuits against loud volumes). But if you want to overcome that you can always use a PC software to increase the rate of volume (at the expense of a higher bitrate which is not a problem for a 256 MB memory card). Talking of cards, Sony has also slashed the prices of Memory Stick Duos so you can upgrade to Memory Stick which is Rs. 2260/- and Rs. 2860/- for 512 MB and 1 GB cards respectively (MRP), so expandability is open. The memory sticks also come with 5 year warranty which is even better.
Make sure you get your Sony Ericsson India warranty card which comes in the box to prevent spurious goods. Many dealers say bill is god enough but why not get it when it is give and makes you secure?