You are probably real close to being able to handle hell. If you have some pgems lying around, you can probably buy everything you need. I'd start by dumpint the tal orb and helm. Without more parts of the set (i.e. amy and armor) its not worth it. But in the mean time - give the tal helm to your merc. The 10% life leech will really help him out.
You're armor is good, if you can "up" it. That will give you around 1000 def, but will cost you a lem+ko+p diamond. Not real cheap if you're on a shoestring budget I know. You can run the countess for the runes, but that will probably take a while. You'll need your merc to kill her too as she's always cold+fire immune.
You can probably pick up a peasant crown for almost nothing - few pgems at most. Check out the trading forums. If you can't find a sorc orb with +2 skills and some fast cast, then make a spirit sword (in a 4os crystal sword). Both the sword and the runes are easy to find.
I'd replace your gloves with either frostburns or magefists. Either can be had for pgems. If you were on US East I'd give you a pair of both. They are dirt cheap, but real useful.
Boots don't really matter for much - other than MF there's no real god mods that a sorc can get from them. If you find a pair that comes with a resist you're missing, +life, +mana and some faster run walk - then go with em.
About the same can be said for a belt. Yes there's arachnids mesh, but its real expensive, so I won't go there. Just try to find the same things I mentioned for boots. Some faster hit recovery never hurts either.
You're shield isn't bad at all. If you are going the max block route than you have the perfect shield. If you aren't planning on spending the stat points to get 75% blocking then I'd say look into a spirit shield.
Try real hard to get your fast cast rate up to 63% minimum. This will really speed up your teleing, which means you don't get hit near as often either. I'm assuming you are having problems getting to meph. That's much harder than actually killing him. (Check out the thread on the "moat trick" stickied in the sorc guide library if you are having any problems killing meph.) The comment on a merc being a pain when meph running is right. You can pretty much count on having him die down there until he's at a pretty high level and has good gear. But for general game play - he's a real help. Check out the guides for cheap merc gear in the library.
The only other thing I can see is that you could stand to level up a little bit more. If you join some public baal run games you can probably get to 85+ real quick. That will be an incremental help.